Co-reporter:Jun Fang Jiang, Juan Qiao, Xiao Yu Mu, Myeong Hee Moon, Li Qi
Talanta 2017 Volume 165() pp:251-257
Publication Date(Web):1 April 2017
DOI:10.1016/j.talanta.2016.12.055
•The magnetic porous polymer membrane was synthesized and characterized.•DAAO enzyme reactor was prepared using the magnetic porous polymer membrane.•The enhanced enzymolysis efficiency of the enzyme reactor was achieved.•The proposed enzyme reactor was applied for DAAO inhibitors screening.In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10 mM, Vmax was 23.8 mM min−1) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors.
Co-reporter:Juan Qiao, Hong Ding, Qianrong Liu, Rongyue Zhang, and Li Qi
Analytical Chemistry 2017 Volume 89(Issue 3) pp:
Publication Date(Web):December 30, 2016
DOI:10.1021/acs.analchem.6b04722
A microfluidic droplet synthesis approach for the preparation of poly N-isopropylacrylamide protected gold nanoparticles (PNIPAm@AuNPs) was presented here. Well-dispersed PNIPAm@AuNPs could be generated within 8 min. On the basis of the aggregation-induced UV–vis adsorption intensity increasing mechanism, the PNIPAm@AuNPs-based colorimetric probe displayed high sensitivity and good selectivity for sensing copper ions. A linear calibration of relative UV–vis adsorption intensity increasing versus copper ions concentration was obtained within 5.0–750.0 μM, and the limit of detection was 2.5 μM. Furthermore, after copper ions were injected in rat, a metabolic assay was developed with the proposed probe. The results indicated that the droplet microfluidic synthesis system could provide a new way for preparation of polymer@AuNPs with good polydispersity index and showed great potential of polymer@AuNPs-based sensing probe for application in biological and clinical analysis.
Co-reporter:Junfang Jiang, Xiaoyu Mu, Juan Qiao, Yuan Su, Li Qi
Talanta 2017 Volume 175(Volume 175) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.talanta.2017.07.052
•Chiral amino amide ionic liquids (CAAILs) were successfully synthesized.•New CLE-CE system was constructed with CAAILs ligands for Dns-D,L-AAs separation.•Well enantioseparation efficiency of the developed CLE-CE was achieved.•The proposed CLE-CE method was applied for determination of enantiomeric purity.Using chiral amino amide ionic liquids as the ligands, a new chiral ligand exchange capillary electrophoresis method with Cu(II) as the central ion was constructed for enantioseparation of labeled D,L-amino acids. The effects of key parameters, including pH value of the running buffer, the ratio of Cu(II) to chiral amino amide ionic liquids, the concentration of complexes based on Cu(II)-chiral amino amide ionic liquids were investigated. It has been observed that eight pairs of labeled D,L-amino acids could be baseline-separated with a running buffer of 15.0 mM ammonium acetate, 10.0 mM Cu(II) and 20.0 mM L-phenylalaninamide based ionic liquid at pH 5.0. The quantitation of D,L-amino acids was conducted and good linearity (r2 ≥ 0.964) was obtained. Furthermore, an assay for determining the enantiomeric purity of D,L-amino acids was developed and the possible enantiorecognition mechanism was discussed briefly. The results indicated that the chiral amino amide ionic liquids could play the role of ligands in chiral ligand exchange capillary electrophoresis system and exhibit great potential in chiral analysis.Download high-res image (197KB)Download full-size image
Co-reporter:Nan Li, Li Qi, Juan Qiao, and Yi Chen
Analytical Chemistry 2016 Volume 88(Issue 3) pp:1821
Publication Date(Web):January 11, 2016
DOI:10.1021/acs.analchem.5b04112
A ratiometric, versatile, and selective fluorescent pattern to sense and distinguish proteins on the basis of dissociation of aqueous polymer-pyrene/γ-cyclodextrin (γ-CD) inclusion complexes was developed. First, two kinds of aqueous polymer-pyrene were prepared via atom transfer radical polymerization using pyrene functionalized initiator. Then, the pyrene molecules could be accumulated into γ-CD cavity and form polymer-pyrene/γ-CD complexes, resulting in appearance of excimer emissions. The resultant complexes responded to proteins in two ways: nonmetalloproteins binding to polymer component triggered dissociation of the inclusion complexes, accompanied by alteration of pyrene excimer/monomer emission and ratiometric fluorescent intensity changes; the presence of metalloproteins could quench pyrene excimer/monomer emission because of energy transfer. Moreover, the fluorescent responses of the inclusion complexes to different proteins could be modulated by changing polymer type and chain length, resulting in a tunable selectivity and sensitivity. The proposed fluorescent inclusion complexes could provide a promising platform for sensing proteins.
Co-reporter:Shilei Ji, Nan Li, Yong Shen, Qi Li, Juan Qiao, Zhibo Li
Analytica Chimica Acta 2016 Volume 909() pp:60-66
Publication Date(Web):25 February 2016
DOI:10.1016/j.aca.2016.01.005
•Poly(MA-L-Ala-OMe) based MIPs for enrichment and release of Lys have been prepared.•Capturing and releasing of Lys could be facilitated by using the thermo-responsive MIPs.•The MIPs have exhibited a great potential in enriching Lys in practical application.In this study, poly(amino acid)-based thermoresponsive molecularly imprinted magnetic nanoparticles for recognition and release of lysozyme was prepared via surface imprinting method. For constructing the molecularly imprinted polymer (MIP) layer, amino acid-based thermoresponsive monomer (N-methacryloyl-l-alanine methyl ester, MA-L-Ala-OMe) was mainly selected for the functional monomer along with N,N′-methylenebis(acrylamide) as the crosslinker. The resultant magnetic MIP nanoparticles were characterized in detail. Meanwhile, the dynamic light scattering studies and swelling ratios measurements were carried out for demonstrating the thermoresponsive property of the imprinted nanoparticles. The prepared magnetic MIP nanoparticles showed good adsorption capacity and selective recognition properties to lysozyme. Moreover, the fast adsorption process could reach equilibrium within 15 min. Importantly, the capture and release of lysozyme could be easily realized simply by altering the temperature of aqueous solution. Furthermore, the prepared imprinted nanoparticles were applied to separate lysozyme from the real egg white samples. The results proved that the thermoresponsive MIPs based on MA-L-Ala-OMe have great potential for selectively enriching target proteins in real samples.
Co-reporter:Juan Qiao, Jin Yong Kim, Yuan Yuan Wang, Li Qi, Fu Yi Wang, Myeong Hee Moon
Analytica Chimica Acta 2016 Volume 906() pp:156-164
Publication Date(Web):4 February 2016
DOI:10.1016/j.aca.2015.11.042
•A porous polymer membrane enzyme reactor was developed.•Breath figure method was used for the fabrication of porous polymer membrane.•The enzyme reactor was coupled to nLC-ESI-MS/MS for proteins on-line digestion.Fast and effective protein digestion is a vital process for mass spectrometry (MS) based protein analysis. This study introduces a porous polymer membrane enzyme reactor (PPMER) coupled to nanoflow liquid chromatography-tandem MS (nLC-ESI-MS/MS) for on-line digestion and analysis of proteins. Poly (styrene-co-maleic anhydride) (PS-co-MAn) was fabricated by the breath figure method to make a porous polymer membrane in which the MAn group was covalently bound to enzyme. Based on this strategy, microscale PPMER (μPPMER) was constructed for on-line connection with the nLC-ESI-MS/MS system. Its capability for enzymatic digestion with bovine serum albumin (BSA) was evaluated with varied digestion periods. The on-line proteolysis of BSA and subsequent analysis with μPPMER-nLC-ESI-MS/MS revealed that peptide sequence coverage increased from 10.3% (digestion time 10 min) to 89.1% (digestion time 30 min). μPPMER can efficiently digest proteins due to the microscopic confinement effect, showing its potential application in fast protein identification and protease immobilization. Applications of on-line digestion using μPPMER with human plasma and urinary proteome samples showed that the developed on-line method yielded equivalent or better performance in protein coverage and identified more membrane proteins than the in-solution method. This may be due to easy accommodation of hydrophobic membrane proteins within membrane pores.
Co-reporter:Juan Qiao, Ping Dong, Xiaoyu Mu, Li Qi, Ran Xiao
Biosensors and Bioelectronics 2016 Volume 78() pp:147-153
Publication Date(Web):15 April 2016
DOI:10.1016/j.bios.2015.11.021
•The reactive polymer PVDMA was synthesized by RAFT polymerization method.•A novel fluorescent nano-conjugates composed of PVDMA, RhB and FA were constructed.•A targeted imaging method for monitoring FR expression in HeLa cells was designed.•The nano-conjugates were applied for up-regulation FR expression study in cells.Thoroughly investigation of folate receptor (FR) expression related to targeting drug delivery in tumor cells has been intensively pursued in recent years. Herein, a simple and versatile strategy for determination of FR expression based on targeted imaging of tumor cells with fluorescent nano-conjugates was developed. The fluorescent nano-conjugates were composed of poly 2-vinyl-4,4-dimethyl azlactone (PVDMA) as the linker, folic acid as the targeting unit and amino-Rhodamine B as the fluorescent ligand. Owing to possessing dimethyl azlactone groups in polymer framework, PVDMA could easily reacted with amines or alcohols, and form water soluble materials. Fluorescent imaging studies indicated that the prepared nano-conjugates could specifically target tumor cells and monitor the over expressing of FR. Moreover, the FR expression up-regulation in HeLa cells through medicines regulation has been further explored. This new protocol opens an effective way through synthesis and design of novel fluorescent nano-conjugates for FR expression investigation in tumor cells via targeted imaging, showing great potential in drug delivery mechanism study and cancer therapy.
Co-reporter:Shilei Ji, Li Qi, Nan Li, Minglin Wang
Talanta 2016 Volume 158() pp:229-234
Publication Date(Web):1 September 2016
DOI:10.1016/j.talanta.2016.05.056
•Novel polymer functionalized Fe3O4@P(MA-L-Phe-OMe) nanoparticles have been prepared.•The proposed nanoparticles have displayed their high affinity to 2,4-D and 4-CPA.•The MSPE sorbents have been applied for enriching plant growth regulators in real samples.A novel magnetic solid phase extraction (MSPE) adsorbent has been developed for enriching two plant growth regulators, including 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chlorophenoxyacetic acid (4-CPA), in bean sprouts. For preparing the MSPE adsorbent, poly(N-methacryloyl-L-phenylalanine methyl ester (P(MA-L-Phe-OMe)), amino acid-based polymer, was modified onto the magnetic nanoparticles via “grafting to” method by free radical polymerization. The resultant P(MA-L-Phe-OMe)-functionalized magnetic nanoparticles (Fe3O4@P(MA-L-Phe-OMe)) were characterized by Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. The adsorption amount of Fe3O4@P(MA-L-Phe-OMe) nanoparticles to 2,4-D and 4-CPA were 39.82 mg g−1 and 29.02 mg g−1, respectively. Moreover, the prepared MSPE adsorbents showed good selectivity towards 2,4-D and 4-CPA due to the hydrophobic interactions and electrostatic forces between the target analytes and Fe3O4@P(MA-L-Phe-OMe). The results demonstrated that the proposed MSPE adsorbents have high affinity to the targets 2,4-D and 4-CPA. Under the optimized conditions, the proposed materials were successfully applied to enrich 2,4-D and 4-CPA in bean sprouts samples. The recovery values of the bean sprouts solution spiked the targets were from 90.9% to 96.4% with the relative standard deviations of 2.3–3.9%. Our work proved that the novel Fe3O4@P(MA-L-Phe-OMe) nanoparticles were the good adsorbents of magnetic solid phase extraction (MSPE) and have good potential for the analysis of trace compound in real samples.
Co-reporter:Juan Qiao, Xiaoyu Mu, Li Qi
Biosensors and Bioelectronics 2016 Volume 85() pp:403-413
Publication Date(Web):15 November 2016
DOI:10.1016/j.bios.2016.04.070
•Design and synthesis of fluorescent polymeric thermometers are summarized.•Polymeric thermometers for intracellular temperature sensing are introduced.•Advantages of these polymeric thermometers for temperature sensing in cells are highlighted.Multitudinous biochemical reactions occur in living cells, creating and releasing free energy to impel numerous cellular activities. Surplus energy is expelled as heat and resulted in elevated temperature, which induce control of gene expression, tumour metabolism and etc. Sensitive measurement of temperature on nanoscale in cells with ideal fluorescent probes is a great challenge in many areas. By taking the advantages of polymers in tunable critical solution temperature range and good biocompatibility, fluorescent polymeric thermometers (FPT) have drawn extensive attention because they are capable of accurate monitoring temperature with high spatial resolution at cellular level. This review offers a general overview of recent examples of FPT working in cells. The strategy for design and synthesis of the FPT has been highlighted. Furthermore, the applications of the constructed FPT for intracellular temperature variations under normal and external stimuli conditions have been discussed. Deep understanding of these aspects would lead to improvement in designing of unique FPT with real function and applications for intracellular temperature sensing. It will pave a new way not only for the study of intrinsic relationship between temperature and organelle function, but also provide the possibility for deep understanding of intracellular biological processes.
Co-reporter:Yaping Li, Li Qi, Nan Li, Huimin Ma
Talanta 2016 Volume 152() pp:244-250
Publication Date(Web):15 May 2016
DOI:10.1016/j.talanta.2016.02.002
•Environmentally benign emulsion cryogelation was used to synthesize polymer monolith.•Poly (GMA-co-EDMA) was developed as a versatile toolbox for diverse applications.•The monolith was applied as a HPLC support for separating various probe molecules.A novel poly (glycidyl methacrylate-co-ethylene dimethacrylate) monolith has been fabricated via the environmental friendly cryogelation-emulsion technique. The polymerization process is assisted by self-assembly of typical tri-block copolymer Pluronic F127 at sub-zero temperature using ice crystal as template, which can avoid consumption of organic porogenic solvents and thermal unstability of emulsion system. The developed monolith possesses hierarchical networks, which is confirmed by nitrogen adsorption measurement, mercury intrusion porosimetry, scanning electron microscopy and permeability testing. Further, the effect of the amounts of Pluronic F127 on the microstructure has been investigated. Moreover, the prepared polymer monolith undergoes acidic hydrolysis of epoxy groups into hydroxyl groups on the surface and its liquid chromatographic performance is explored by separating model analytes. The results indicate that the unique porous polymer monolith with hierarchical networks could be prepared via an organic porogen-free approach and used for analysis of polar and nonpolar molecules, extending the application of cryogelation-emulsion technique and methacrylate-based monolith.
Co-reporter:Juan Qiao, Yoon-Ho Hwang, Chuan-Fang Chen, Li Qi, Ping Dong, Xiao-Yu Mu, and Dong-Pyo Kim
Analytical Chemistry 2015 Volume 87(Issue 20) pp:10535
Publication Date(Web):September 22, 2015
DOI:10.1021/acs.analchem.5b02791
Intracellular temperature has a fundamental effect on cellular events. Herein, a novel fluorescent polymer ratiometric nanothermometer has been developed based on transferrin protein-stabilized gold nanoclusters as the targeting and fluorescent ratiometric unit and the thermosensitve polymer as the temperature sensing unit. The resultant nanothermometer could feature a high and spontaneous uptake into the HeLa cells and the ratiometric temperature sensing over the physiological temperature range. Moreover, the precise temperature sensing for intracellular heat generation in HeLa cells following calcium ions stress has been achieved. This practical intracellular thermometry could eliminate the interference of the intracellular surrounding environment in cancer cells without a microinjection procedure, which is user-friendly. The prepared new nanothermometer can provide tools for unveiling the intrinsic relationship between the intracellular temperature and ion channel function.
Co-reporter:Xiaozhe Xu, Juan Qiao, Nan Li, Li Qi, Shufeng Zhang
Analytica Chimica Acta 2015 Volume 879() pp:97-103
Publication Date(Web):16 June 2015
DOI:10.1016/j.aca.2015.03.036
•A novel fluorescent probe based on ensemble of AuNCs and polymer protected AuNPs was developed.•The proposed fluorescent probe could be used for turn-on sensing of l-Cys.•The l-Cys in urine samples was monitored by this fluorescent probe.A new fluorescent probe based on ensemble of gold nanoclusters (AuNCs) and polymer protected gold nanoparticles (AuNPs) for turn-on sensing of l-cysteine was designed and prepared. The AuNCs were protected by bovine serum albumin and had strong fluorescence. The polymer protected AuNPs were synthesized by a facile in situ strategy at room temperature and could quench the fluorescence of AuNCs due to the Förster resonance energy transfer. Interestingly, it has been observed that the quenched fluorescence of AuNCs was recovered by l-cysteine, which could induce the aggregation of polymer protected AuNPs by sulfur group. Then the prepared fluorescent probe was successfully used for determination of l-Cys in human urines, which would have an evolving aspect and promote the subsequent exploration.
Co-reporter:Nan Li, Yong Shen, Li Qi, Zhibo Li, Juan Qiao and Yi Chen
RSC Advances 2015 vol. 5(Issue 75) pp:61436-61439
Publication Date(Web):09 Jul 2015
DOI:10.1039/C5RA12203A
A versatile method for preparing a reverse phase/weak anion exchange/hydrophilic interaction trimodal polymer monolith was proposed by the one-step copolymerization of amino acid-based monomer and N,N′-methylenebisacrylamide. The retention mechanisms of the resultant monolith were evaluated using different series of small molecules. Furthermore, the separation of protein mixtures could be easily achieved under isocratic elution. The proposed polymer monolith, which has the merits of easy preparation, low mass transfer resistance and good biocompatibility, is a promising separation medium for small and large molecules.
Co-reporter:Yuan Su, Xiaoyu Mu and Li Qi
RSC Advances 2015 vol. 5(Issue 36) pp:28762-28768
Publication Date(Web):24 Mar 2015
DOI:10.1039/C5RA02744F
L-Alanine (L-Ala) derived amino acid ionic liquids (AAILs) were synthesized successfully and applied as new chiral ligands in a chiral ligand exchange capillary electrophoresis (CLE-CE) system. With Mn(II)–AAIL complexes and β-cyclodextrin (β-CD) as the dual chiral selectors, a CLE-CE system was further developed for enantioseparation of dansyl D,L-amino acids (Dns-D,L-AAs). The influence of different separation parameters in CLE-CE, including the different kinds of AAILs, pH of the running buffer, the ratio of Mn(II) to AAILs, the concentration of complexes and β-CD were investigated and the optimum buffer was obtained: 100.0 mM boric acid, 5.0 mM ammonium acetate, 2.5 mM Mn(II), 5.0 mM [1-butyl-3-methylimidazolium][L-Ala] and 5.0 mM β-CD at pH 8.3. Under the optimum conditions, twelve pairs of Dns-D,L-AAs could be baseline separated and six pairs were partly separated. Additionally, a control study between the performance of Mn(II)–L-Ala and Mn(II)–[1-butyl-3-methylimidazolium][L-Ala] complexes was conducted to prove the unique behavior of AAILs in CLE-CE. Moreover, the proposed CLE-CE method was applied in screening tyrosinase inhibitors with benzoic acid and its derivatives as the typical compounds. The results illustrated that the CDs acting synergistically with the CLE-CE system could produce better performance on enantioseparation, and the novel CLE-CE method has great application potential in enzyme analysis.
Co-reporter:Lulu Xun, Juan Qiao, Li Qi, Jie Huang and Huiwu Cai
Analytical Methods 2015 vol. 7(Issue 23) pp:9906-9911
Publication Date(Web):21 Oct 2015
DOI:10.1039/C5AY02483H
A facile and green strategy has been developed for the in situ synthesis of polyacrylamide (PAM)-protected gold nanoparticles (AuNPs). A PAM polymer with thiol-terminated groups was prepared using the reversible addition–fragmentation chain transfer radical polymerization method. The PAM with thiol-terminated groups was able to capture gold ions to form PAM-AuNPs, which displayed a specific response to manganese ions in aqueous solution. The binding forces between the PAM and the manganese ions caused the PAM-AuNPs to move closer together, decreasing the interparticle distance and forming aggregates with a small red shift in the UV-visible absorption band. Dynamic light scattering analysis showed an obviously increased surface charge for the PAM-AuNPs when they were exposed to manganese ions, which could cause cross-linking aggregation. The PAM-AuNPs were used for the determination of manganese ions in the linear range 8.0–500 μmol L−1 with a limit of detection of 5.0 μmol L−1. These aggregates therefore provide a promising assay for the determination of manganese ions in real water samples.
Co-reporter:Lu-Liang Wang;Juan Qiao;Xiao-Zhe Xu;Dan Li
Science China Chemistry 2015 Volume 58( Issue 9) pp:1508-1514
Publication Date(Web):2015 September
DOI:10.1007/s11426-015-5354-5
Protein protected gold nanoclusters have outstanding physical and chemical properties that make them excellent scaffolds for the construction of novel chemical and biological probes. In this study, a simple one-pot synthesis method was proposed for the preparation of fluorescent probes based on ovalbumin-stabilized gold nanoclusters. This strategy allowed the generation of water-soluble gold nanoclusters within 5 min. The as-prepared fluorescent probe exhibited a red fluorescence emission at 625 nm, and good thermostability. The fluorescent probe was applied to measure glucose concentrations based on the hydrogen peroxide-induced fluorescence quenching principle, and showed favorable biocompatibility, high sensitivity and good selectivity. As a result of the advantageous properties and performance of this fluorescent probe, the present assay allowed for the selective determination of glucose in the range of 5.0×10−6 to 10.0×10−3 mol/L with a detection limit of 1.0×10−6 mol/L. Moreover, the glucose content in urinary samples was analyzed using the constructed fluorescent probe: this indicated the potential of the fluorescent gold nanoclusters for applications in biological and clinical diagnosis and therapy.
Co-reporter:Juan Qiao, Chuanfang Chen, Li Qi, Meirong Liu, Ping Dong, Qin Jiang, Xinzheng Yang, Xiaoyu Mu and Lanqun Mao
Journal of Materials Chemistry A 2014 vol. 2(Issue 43) pp:7544-7550
Publication Date(Web):08 Sep 2014
DOI:10.1039/C4TB01154F
Intracellular temperature imaging could help to understand diverse biological reactions and functions in living cells. Herein, we report a nanothermometer based on ratiometric fluorescent polymers (RFPs) synthesized by the living/controlled reversible addition–fragmentation transfer polymerization method for intracellular temperature sensing. The thermometer was composed of a thermo sensitive polymer, a polarity sensitive fluorescent dye and a thermo insensitive fluorescent dye. With the increasing temperature, the fluorescent intensity of RFPs increased because of the fluorescent intensity enhancement of the polarity sensitive fluorescent dye induced by the self assembling of the thermo sensitive polymer. The prepared RFPs exhibited a fluorescence “turn-on” response at higher temperature. We further investigated the simultaneous temperature sensing and the ratiometric imaging of temperature variations associated with biological processes in living cells using this novel ratiometric probe. The polymer based ratiometric fluorescent thermometer can be used to precisely measure the temperature in living cells, and shows great potential in spatio-temporal temperature sensing down to the nanoscale within biological systems.
Co-reporter:Xiaoyu Mu, Juan Qiao, Li Qi, Ping Dong, and Huimin Ma
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 23) pp:21346
Publication Date(Web):October 31, 2014
DOI:10.1021/am5063025
Fabrication of various efficient enzyme reactors has triggered increasing interests for its extensive applications in biological and clinical research. In this study, magnetic nanoparticles were functionalized by a biocompatible reactive polymer, poly(2-vinyl-4,4-dimethylazlactone), which was synthesized by reversible addition–fragmentation chain transfer polymerization. Then, the prepared polymer-modified magnetic nanoparticles were employed as favorable carriers for enzyme immobilization. l-Asparaginase was selected as the model enzyme to fabricate the enzyme reactor, and the prepared enzyme reactor exhibited high loading capacity of 318.0 μg mg–1 magnetic nanoparticle. Interestingly, it has been observed that the enzymolysis efficiency increased slightly with the lengthened polymer chain, resulting from the increased immobilization amount of enzyme. Meanwhile, the immobilized enzyme could retain more than 95.7% activity after 10 repeated uses and maintain more than 72.6% activity after 10 weeks storage. Moreover, an extracorporeal shunt system was simulated to estimate the potential application capability of the prepared l-asparaginase reactor in acute lymphoblastic leukemia treatment.Keywords: enzyme immobilization; l-asparaginase; magnetic nanoparticles; poly(2-vinyl-4,4-dimethylazlactone)
Co-reporter:Nan Li, Li Qi, Ying Shen, Juan Qiao, and Yi Chen
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 19) pp:17289
Publication Date(Web):September 8, 2014
DOI:10.1021/am505427j
In this study, oligo(ethylene glycol) (OEG)-based thermoresponsive molecularly imprinted polymers (MIPs) for lysozyme on the surface of magnetic nanoparticles were synthesized. Thermoresponsive monomer 2-(2-methoxyethoxy)ethyl methacrylate, chelate monomer N-(4-vinyl)-benzyl iminodiacetic acid, and acidic monomer methacrylic acid were selected as the ingredients for preparing the MIP layer. The thermoresponsive behavior of the novel imprinted magnetic nanoparticles was evaluated by dynamic light scattering and swelling ratios measurements. Interestingly, in analysis of lysozyme, the capture/release process could be modulated by changing the temperature, avoiding tedious washing steps. Meanwhile, high adsorption capacity (204.1 mg/g) and good selectivity for capturing lysozyme were achieved. Additionally, surface imprinting with magnetic nanoparticles as substrate allowed for short adsorption time (2 h) and rapid magnetic separation. Furthermore, the proposed imprinted magnetic nanoparticles were used to selectively extract lysozyme in human urine with recoveries ranging from 89.2% to 97.3%. The results indicated that the OEG-based monomers are promising for responsive MIP preparation, and the proposed imprinted material is efficient for thermally modulated capture and release of target protein.Keywords: lysozyme; magnetic nanoparticles; oligo(ethylene glycol)-based monomers; surface imprinting; thermoresponsive molecularly imprinted polymer
Co-reporter:Xiaoyu Mu, Juan Qiao, Li Qi, Ying Liu, and Huimin Ma
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 15) pp:12979
Publication Date(Web):July 1, 2014
DOI:10.1021/am502901b
Developing facile and high-throughput methods for exploring pharmacological inhibitors of d-amino acid oxidase (DAAO) has triggered increasing interest. In this work, DAAO was immobilized on the magnetic nanoparticles, which were modified by a biocompatible reactive polymer, poly(glycidyl methacrylate) (PGMA) via an atom transfer radical polymerization technique. Interestingly, the enzyme immobilization process was greatly promoted with the assistance of a lithium perchlorate catalyst. Meanwhile, a new amino acid ionic liquid (AAIL) was successfully synthesized and employed as the efficient chiral ligand in a chiral ligand exchange capillary electrophoresis (CLE-CE) system for chiral separation of amino acids (AAs) and quantitation of methionine, which was selected as the substrate of DAAO. Then, the apparent Michaelis–Menten constants in the enzyme system were determined with the proposed CLE-CE method. The prepared DAAO-PGMA-Fe3O4 nanoparticles exhibited excellent reusability and good stability. Moreover, the enzyme reactor was successfully applied in screening DAAO inhibitors. These results demonstrated that the enzyme could be efficiently immobilized on the polymer-grafted magnetic nanoparticles and that the obtained enzyme reactor has great potential in screening enzyme inhibitors, further offering new insight into monitoring the relevant diseases.Keywords: d-amino acid oxidase; enzyme immobilization; magnetic nanoparticles; polymer; screening inhibitors
Co-reporter:Lu-Liang Wang, Juan Qiao, Hui-Hui Liu, Jie Hao, Li Qi, Xiao-Ping Zhou, Dan Li, Zong-Xiu Nie, and Lan-Qun Mao
Analytical Chemistry 2014 Volume 86(Issue 19) pp:9758
Publication Date(Web):August 26, 2014
DOI:10.1021/ac5023293
Glucose monitoring with high sensitivity and accuracy in the cerebrospinal fluid is a challenge for evaluating the role of glucose in the physiological and pathological processes. In this work, a ratiometric fluorescent probe for sensing glucose was developed. In the probe, the gold nanoclusters protected by ovalbumin played the role as the reference of fluorophore and the Alizarin Red S-3-aminophenyl boronic acid immobilized on the poly(N-acryloxysuccinimide) acted as both the response signal and specific recognition unit for sensing glucose. Once the ratiometric fluorescent probe reacted with glucose in the biological system, its fluorescence intensity at 567 nm was quenched, while the fluorescence intensity at 610 nm was essentially unchanged. In addition, the prepared ratiometric fluorescent probe showed higher stability against environmental effects. As a result, the present ratiometric fluorescent probe was successfully used for monitoring of glucose in the rat brain following the cerebral calm/ischemia.
Co-reporter:Yaping Li, Li Qi, Ying Shen, Huimin Ma
Analytica Chimica Acta 2014 Volume 811() pp:36-42
Publication Date(Web):6 February 2014
DOI:10.1016/j.aca.2013.12.020
•The core@shell Fe3O4@Au nanoparticles functionalized with SAMs were successfully constructed.•The SAMs could be transformed from one kind to another via thiol exchange process.•The developed nanomaterials could be applied in mode switching MSPE.The core@shell Fe3O4@Au nanoparticles (NPs) functionalized with exchangeable self-assembled monolayers have been developed for mode switching magnetic solid-phase extraction (MSPE) using high performance liquid chromatography with ultraviolet detection. The adsorbents were synthesized by chemical coprecipitation to prepare magnetic cores followed by sonolysis to produce gold shells. Functionalization of Fe3O4@Au NPs surface was realized through self-assembly of commercially available low molecular weight thiol-containing ligands using gold shells as intermediate platform and the dynamic nature of Au–S chemistry allowed substituent of one thiol-containing ligand with another simply by thiol exchange process. The resultant adsorbents were characterized by transmission electronic microscopy, Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and vibrating sample magnetometry. To evaluate the versatile performance of the developed MSPE adsorbents, they were applied for normal-phase SPE followed by reversed-phase SPE. A few kinds of diphenols and polycyclic aromatic hydrocarbons (PAHs) were employed as model analytes, respectively. The predominant parameters affecting extraction efficiency were investigated and optimized. Under the optimum experimental conditions, wide dynamic linear range (6.25–1600 μg L−1 for diphenols and 1.56–100 μg L−1 for PAHs) with good linearity (r2 ≥ 0.989) and low detection limits (0.34–16.67 μg L−1 for diphenols and 0.26–0.52 μg L−1 for PAHs) were achieved. The advantage of the developed method is that the Fe3O4@Au NPs could be reutilized for preconcentrating diverse target analytes in different SPE modes sequentially simply through treatment with desired thiol-containing ligands.
Co-reporter:Xiaoyu Mu, Li Qi, Juan Qiao, Xinzheng Yang, Huimin Ma
Analytica Chimica Acta 2014 Volume 846() pp:68-74
Publication Date(Web):10 October 2014
DOI:10.1016/j.aca.2014.07.022
•A new CLE-CE system was developed coordinating with γ-CD.•The proposed method was applied in chiral separation of AAs and dipeptides.•The enantiomeric purity of AAs and dipeptides was determined by this method.•The possible enantiorecognition mechanism was explored and discussed.A chiral ligand exchange capillary electrophoresis (CLE-CE) method using Zn(II) as the central ion and l-4-hydroxyproline as the chiral ligand coordinating with γ-cyclodextrin (γ-CD) was developed for the enantioseparation of amino acids (AAs) and dipeptides. The effects of various separation parameters, including the pH of the running buffer, the ratio of Zn(II) to l-4-hydroxyproline, the concentration of complexes and cyclodextrins (CDs) were systematically investigated. After optimization, it has been found that eight pairs of labeled AAs and six pairs of labeled dipeptides could be baseline-separated with a running electrolyte of 100.0 mM boric acid, 5.0 mM ammonium acetate, 3.0 mM Zn(II), 6.0 mM l-hydroxyproline and 4.0 mM γ-CD at pH 8.2. The quantitation of AAs and dipeptides was conducted and good linearity (r2 ≥ 0.997) and favorable repeatability (RSD ≤ 3.6%) were obtained. Furthermore, the proposed method was applied in determining the enantiomeric purity of AAs and dipeptides. Meanwhile, the possible enantiorecognition mechanism based on the synergistic effect of chiral metal complexes and γ-CD was explored and discussed briefly.
Co-reporter:Bingbing Sun, Xiaoyu Mu, Li Qi
Analytica Chimica Acta 2014 Volume 821() pp:97-102
Publication Date(Web):22 April 2014
DOI:10.1016/j.aca.2014.03.009
•Novel amino acid ionic liquids with pyridinium as cations and l-lysine as anion were synthesized.•These synthesized AAILs have been explored as the ligands coordinated with Zn(II) in CLE-CE system.•The developed CLE-CE method could be used for the enantioseparation of Dns-d, l-amino acids.•The kinetic contents of l-amino acid oxidase were investigated with the proposed CLE-CE system.New kinds of amino acid ionic liquids (AAILs) with pyridinium as cations and l-lysine (l-Lys) as anion have been developed as the available chiral ligands coordinated with Zn(II) in chiral ligand-exchange capillary electrophoresis (CLE-CE). Four kinds of AAILs, including [1-ethylpyridinium][l-lysine], 1-butylpyridinium][l-lysine], [1-hexylpyridinium][l-lysine] and 1-[octylpyridinium][l-lysine], were successfully synthesized and characterized by nuclear magnetic resonance and mass spectrometry. Compared with other AAILs, the best chiral separation of Dns-d, l-amino acids could be achieved when [1-ethylpyridinium][l-lysine] was chosen as the chiral ligand. It has been found that after investigating the influence of key factors on the separation efficiency, such as pH of buffer solution, the ratio of Zn(II) to ligand and complex concentration, eight pairs of Dns-d, l-AAs enantiomers could be baseline separated and three pairs were partly separated under the optimum conditions. The proposed CLE-CE method also exhibited favorable quantitative analysis property of Dns-d, l-Met with good linearity (r2 = 0.998) and favorable repeatability (RSD ≤ 1.5%). Furthermore, the CLE-CE system was applied in investigating the kinetic contents of l-amino acid oxidase, which implied that the proposed system has the potential in studying the enzymatic reaction mechanism.
Co-reporter:Bingbing Sun;Minglin Wang
Journal of Separation Science 2014 Volume 37( Issue 16) pp:2248-2252
Publication Date(Web):
DOI:10.1002/jssc.201400444
A capillary electrophoresis method for separating preservatives with various ionic liquids as the electrolyte additives has been developed. The performances for separation of the preservatives using five ionic liquids with different anions and different substituted group numbers on imidazole ring were studied. After investigating the influence of the key parameters on the separation (the concentration of ionic liquids, pH, and the concentration of borax), it has been found that the separation efficiency could be improved obviously using the ionic liquids as the electrolyte additives and tested preservatives were baseline separated. The proposed capillary electrophoresis method exhibited favorable quantitative analysis property of the preservatives with good linearity (r2 = 0.998), repeatability (relative standard deviations ≤ 3.3%) and high recovery (79.4–117.5%). Furthermore, this feasible and efficient capillary electrophoresis method was applied in detecting the preservatives in soft drinks, introducing a new way for assaying the preservatives in food products.
Co-reporter:Nan Li;Wei Zheng;Ying Shen;Yaping Li;Juan Qiao;Fuyi Wang;Yi Chen
Journal of Separation Science 2014 Volume 37( Issue 23) pp:3411-3417
Publication Date(Web):
DOI:10.1002/jssc.201400794
Novel porous polymer monoliths grafted with poly{oligo[(ethylene glycol) methacrylate]-co-glycidyl methacrylate} brushes were fabricated via two-step atom-transfer radical polymerization and used as a trypsin-based reactor in a continuous flow system. This is the first time that atom-transfer radical polymerization technique was utilized to design and construct polymer monolith bioreactor. The prepared monoliths possessed excellent permeability, providing fast mass transfer for enzymatic reaction. More importantly, surface properties, which were modulated via surface-initiated atom-transfer radical polymerization, were found to have a great effect on bioreactor activities based on Michaelis–Menten studies. Furthermore, three model proteins were digested by the monolith bioreactor to a larger degree within dramatically reduced time (50 s), about 900 times faster than that by free trypsin (12 h). The proposed method provided a platform to prepare porous monoliths with desired surface properties for immobilizing various enzymes.
Co-reporter:Yuan Su, Xiaoyu Mu and Li Qi
RSC Advances 2014 vol. 4(Issue 98) pp:55280-55285
Publication Date(Web):17 Oct 2014
DOI:10.1039/C4RA09433F
Tyrosinase plays a key role in melanin formation, and it is closely related to hyper pigmentation in animals and enzymatic browning in food. Thus, it is of great significance to screen inhibitors of tyrosinase. In this work, a new chiral ligand exchange-capillary electrophoresis (CLE-CE) system based on the coordination effect of Zn(II)–L-leucine complexes and β-cyclodextrin (β-CD) was developed for screening the inhibitors of tyrosinase. The effects of the concentration of β-CD, buffer pH, the ratio of L-leucine to Zn(II), and the complex concentration were investigated with Dns-D,L-tyrosine, Dns-D,L-valine and Dns-D,L-phenylalanine as the tested analytes. The optimum buffer conditions were composed of 100.0 mM boric acid, 5.0 mM ammonium acetate, 3.0 mM Zn(II), 6.0 mM L-leucine and 4.0 mM β-CD at pH 8.2. It has been found that six pairs of Dns-D,L-AAs could be baseline-separated and five pairs of Dns-D,L-AAs were partly enantioseparated. Then the quantitative analysis of L-tyrosine was conducted and good linearity (r2 = 0.992) was obtained with a concentration ranging from 12.95 μM to 413.3 μM. A kinetics study of tyrosinase was realized, and the Km and Vmax were 636 μM and 312 μmol min−1 mg−1. Moreover, the proposed method was applied in screening the inhibitors of tyrosinase with four kinds of chalcones as the model inhibitors. The results demonstrated that the developed CLE-CE system was favorable for screening enzyme inhibitors, and showed great potential in related drugs discovery and clinical analysis in the future.
Co-reporter:Yaping Li;Ying Shen;Haizhi Zhang;Huimin Ma
Chinese Journal of Chemistry 2014 Volume 32( Issue 7) pp:619-625
Publication Date(Web):
DOI:10.1002/cjoc.201400188
Abstract
A novel polymeric ionic liquid grafted porous polymer monolith has been facilely fabricated for mixed-mode chromatography. The column is prepared from poly (glycidyl methacrylate-co-ethylene dimethacrylate) monolith through hydrolyzation of the epoxy moieties into hydroxyl groups, followed by "grafting from" polymerization of ionic liquid of 1-vinyl-3-butylimidazolium chloride. Successful modification is characterized by scanning electron microscope, infrared spectroscopy, elemental analysis and mercury intrusion porosimetry. The HPLC performance of developed column is evaluated by separating acidic vitamin B analytes, neutral steroids and basic aromatic amines in mixed-mode chromatography on a single column, respectively. The ionic liquid affords the monolith with both enhanced separation ability and improved column efficiency.
Co-reporter:Xiaoyu Mu, Li Qi, Juan Qiao and Huimin Ma
Analytical Methods 2014 vol. 6(Issue 16) pp:6445-6451
Publication Date(Web):09 Jun 2014
DOI:10.1039/C4AY01137F
The simplicity of the one-pot green synthesis routine and the capability of surface modification of various bioactive molecules make gold nanoclusters (Au NCs) highly suitable as scaffolds for the construction of novel chemical and biological sensors. In this work, we report a novel strategy to prepare amino acid stabilized fluorescent Au NCs via a green one-pot process. The obtained Au NCs possessed light green fluorescence with maximum emission at 498 nm and their quantum yield (QY) was evaluated to be 1.68%. Subsequently, the developed fluorescent Au NC biosensor allowed sensitive and selective detection of Fe3+ ions based on fluorescence quenching with a detection limit of 0.2 μM and Al3+ ions based on enhanced fluorescence with a detection limit of 0.3 μM, respectively. Furthermore, we testified the feasibility of applying this fluorescent probe for real sample analysis through the detection of Al3+ ions and Fe3+ ions in lake water, pond water and tap water. These results indicated that the as-prepared Au NCs had great potential to be developed as the favorable sensor for detection of metal ions in real samples.
Co-reporter:Juan Qiao, Xiaoyu Mu and Li Qi
Journal of Materials Chemistry A 2013 vol. 1(Issue 42) pp:5756-5761
Publication Date(Web):19 Sep 2013
DOI:10.1039/C3TB21169J
In this work, we present a facile in situ strategy for synthesis of thermo-responsive gold nanoparticles (GNPs) at room temperature. By using the RAFT polymerization methods, thermo-responsive polymer chains possessing trithiocarbonate groups have been synthesized which can be split into two chains and can produce a thiol end-group by NaOH. Then the thiol end-group polymer chains can act as anchors to capture the Au(III) ions in aqueous solution to form thermo-responsive GNPs. The thermo-responsive GNPs synthesized by the proposed method exhibited a reversible, clear–opaque transition in solution between 35 °C and 60 °C. It is conjectured that this strategy possesses the virtues including in situ, “green”, universal and tailored without a tedious reducing procedure using any toxic reducing agents. Further, the thermo-responsive GNPs have been applied for the effective analysis of cysteine in urine samples.
Co-reporter:Ying Shen, Wei Guo, Li Qi, Juan Qiao, Fuyi Wang and Lanqun Mao
Journal of Materials Chemistry A 2013 vol. 1(Issue 17) pp:2260-2267
Publication Date(Web):25 Feb 2013
DOI:10.1039/C3TB20116C
The effort to stabilize enzymes and improve their activity has generated great interest because of their wide application in proteomics research, bioenergy conversion, bioassays and so on. In this work, biocompatible reactive polymer, poly (glycidyl methacrylate), grafted from magnetic nanoparticles by atom transfer radical polymerization method, has been firstly proposed to immobilize enzymes for microwave-assisted digestion. Meanwhile, trypsin was chosen as a model enzyme. Resulting from the increased functionality, the immobilization amount of the enzyme on the magnetic nanoparticle surface has been greatly improved. Furthermore, the enzyme immobilized magnetic nanoparticles have exhibited excellent repeatability and stability. The influence of the polymer chain length on digestion efficiency has been investigated both at 37 °C and under microwave. It has been found that the digestion efficiency increases with the lengthened polymer brushes due to the increased immobilization amount. Utilizing cytochrome C as a model protein for digestion, the performance of this immobilized biocatalyst has been demonstrated and this digestion assisted with microwave could be completed within 15 s. This study offers insight into the design of polymer brushes on the surface of magnetic nanoparticles for high digestion efficiency in the future.
Co-reporter:Nan Li, Li Qi, Ying Shen, Yaping Li, and Yi Chen
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 23) pp:12441
Publication Date(Web):November 20, 2013
DOI:10.1021/am403510g
Porous polymer monoliths onto which were grafted a thermoresponsive copolymer, poly(2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA)-co-oligo(ethylene glycol) methacrylate (OEGMA)), were synthesized by the two-step atom transfer radical polymerization (ATRP) method. The copolymer-grafted monoliths were characterized by elemental analysis, scanning electron microscopy, and mercury intrusion porosimetry. They were further used as the thermoresponsive stationary phase for all-aqueous high-performance liquid chromatography (HPLC). The chromatograms of three steroids demonstrated that the chain length of the grafted copolymer, which was regulated by varying the grafting time, could affect the separation by providing different amounts of hydrophobic interaction sites with analytes. Additionally, the elution profiles of steroids on the stationary phase could also be tuned by the comonomer composition. The results showed that the porous polymer monoliths enabled separation of the test mixture in pure aqueous mobile phase under isocratic conditions. Furthermore, the proposed method provides a simple and promising tool in the design and construction of responsive surfaces for chromatography applications.Keywords: hydrophobic interaction; poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol) methacrylate) brushes; separation; thermoresponsive monolith; two-step atom transfer radical polymerization;
Co-reporter:Juan Qiao, Xiaoyu Mu, Li Qi, Jingjing Deng and Lanqun Mao
Chemical Communications 2013 vol. 49(Issue 73) pp:8030-8032
Publication Date(Web):05 Jul 2013
DOI:10.1039/C3CC44256J
A novel nano-conjugate containing ultrasmall water-soluble AuNCs protected by ovalbumin as the fluorescent part, folic acid as the targeting ligand and a homopolymer N-acryloxysuccinimide as the linker has been investigated. Moreover, specific staining of HeLa cells by the nano-conjugate has been demonstrated.
Co-reporter:Yaping Li, Li Qi and Huimin Ma
Analyst 2013 vol. 138(Issue 18) pp:5470-5478
Publication Date(Web):11 Jun 2013
DOI:10.1039/C3AN01122D
A newly developed porous polymer monolith was prepared through copolymerization of 3-(trimethoxysilyl)propylmethacrylate modified graphene oxide with glycidyl methacrylate and ethylene dimethacrylate as a functional crosslinker, which was synthesized through silanization reaction of graphene oxide prepared by Hummers method with 3-(trimethoxysilyl)propylmethacrylate. The monolith was characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, mercury intrusion porosimetry and nitrogen adsorption measurement. The monolith column was applied as the stationary phase of high performance liquid chromatography and its chromatographic performance was evaluated by separation of small molecules in the isocratic reversed-phase mode. The chromatograms of hydrophobic steroids and polar aromatic amines on the prepared monolith displayed the enhanced separation performance over those on the parent monolith. The reproducibility of the column was less than 3.5% in terms of relative standard deviation of retention time. The results demonstrate that copolymerization of functionalized graphene oxide into porous polymer monolith was an effective tool for chromatography separation enhancement of small molecules in an isocratic mode.
Co-reporter:Nan Li, Li Qi, Ying Shen, Yaping Li, Yi Chen
Journal of Chromatography A 2013 Volume 1316() pp:1-7
Publication Date(Web):5 November 2013
DOI:10.1016/j.chroma.2013.09.030
•A novel method for microwave-assisted extraction of PAHs has been developed.•Amphiphilic block copolymer modified Fe3O4 nanoparticles were used as the adsorbents.•The extraction procedure requires short time and provides operational convenience.In this work, amphiphilic block copolymer poly(tert-butyl methacrylate)-block-poly(glycidyl methacrylate) (PtBMA-b-PGMA) modified Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) were synthesized, and served as an adsorbent for microwave-assisted extraction of polycyclic aromatic hydrocarbons (PAHs). The PtBMA-b-PGMA block copolymers with different block ratios were prepared by two-step atom transfer radical polymerization (ATRP) and the extraction abilities of their corresponding Fe3O4@PtBMA-b-PGMA were investigated. The key factors affecting the extraction efficiency of the adsorbent, including microwave conditions, amount of adsorbent, type and volume of desorption solvent, were studied in detail. In comparison with vortex, which is a conventional method used for assisting extraction, the proposed microwave-assisted method allowed better extraction efficiency and required a shorter extraction time. The calibration curves of PAHs were obtained in the range of 0.05–120 μg/L (r > 0.9985) and the limits of detection (S/N = 3) were in the range of 2.4–6.3 ng/L. The recoveries of PAHs spiked in environmental water samples were between 62.5% and 104% with relative standard deviations (RSDs) ranging from 0.84% to 9.02%. The proposed technique combining microwave-assisted extraction and magnetic separation was demonstrated to be a fast, convenient and sensitive pretreating method for PAHs.
Co-reporter:Bingbing Sun;Yaping Li;Juan Qiao;Minglin Wang
Journal of Separation Science 2013 Volume 36( Issue 21-22) pp:3629-3634
Publication Date(Web):
DOI:10.1002/jssc.201300822
A new and simple open-tubular CEC (OT-CEC) method with a novel diblock copolymer poly(butyl methacrylate)71-block-poly(glycidyl methacrylate)9 as the coating based on its self-assembled properties has been developed. Compared with the bare capillary, this coating could act as a surfactant and improve the separation efficiency of aromatic amines. Meanwhile, the effects of pH value, buffer concentration, and the copolymer block ratio on the separation efficiencies were investigated in detail. It has been found that the three tested aromatic amines could be baseline separated by the OT-CEC method with the cooperation of SDS. The proposed OT-CEC method showed good repeatability with RSDs <3.2% for testing the EOF. Moreover, it was also well validated by satisfactory linearity and favorable recovery, which ensured its successful application in the separation of aromatic amines in nail polish samples. The results revealed the potential applicability of the OT-CEC method in cosmetic analysis.
Co-reporter:Haizhi Zhang;Xiaoyu Mu;Xiaoping Zhou;Dan Li;Lanqun Mao
Journal of Separation Science 2013 Volume 36( Issue 5) pp:886-891
Publication Date(Web):
DOI:10.1002/jssc.201200908
In this work, investigation of the comparative influence of diverse ionic liquids (ILs) as electrolyte additives on the chiral separation of dansylated amino acids by using Zn(II)-L-arginine complex mediated chiral ligand exchange CE (CLE-CE) was conducted. It has been found that not only the varied substituted group number, but also the alkyl chain length of the substituted group on imidazole ring in the structure of ILs show different influence on chiral separation of the analytes in the CLE-CE system, which could be understood by their direct influence on EOF. Meanwhile, the variation of anion in the structure of ILs displayed remarkably changed performance and the ILs with Cl− showed the most obvious promoting effect on the chiral separation performance. Among the investigated seven ILs, 1-butyl-3-methylimidazolium chloride was validated to be the proper electrolyte additive in the CLE-CE system. Moreover, it has been observed that 1-butyl-3-methylimidazolium chloride also has obvious promotive effect on the labeling performance. The results have demonstrated that the ILs with different structures have important relation to their performance in CLE-CE and to their labeling efficiency in dansylation of the analytes.
Co-reporter:Jun Yang;Yi Chen;Huimin Ma
Chinese Journal of Chemistry 2013 Volume 31( Issue 2) pp:209-214
Publication Date(Web):
DOI:10.1002/cjoc.201200922
Abstract
In this work, we present a three dimensional micromixer which consists of two layers of spiral channels overlapped together in the vertical direction. This micromixer is designed by using a smooth channel twisted into double-layer spiral geometry with simple topological structure. Based on the principle of Dean effects, this kind of structure is beneficial to produce, enhance and sustain the Dean vortices, which can perturb the laminar fluid effectively. In order to improve the mixing performance, the detailed parameters have been optimized by using the computational fluid dynamics software. The results indicate that the erect channel which is connected with the two layers of spiral channels plays a critical role for well mixing. Meanwhile, the effect of mixing has been identified in a fabricated glass-micromixer. The mixing ef?ciency of 90% has been achieved by optimizing the flow rate and the structure of the erect channel. Thus, this micromixer has manifested high mixing efficiency and presents good practicability in the versatile microfluidic systems.
Co-reporter:Jun Yang;Yi Chen;Huimin Ma
Chinese Journal of Chemistry 2013 Volume 31( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/cjoc.201390004
Co-reporter:Xiaoyu Mu, Li Qi, Ping Dong, Juan Qiao, Jian Hou, Zongxiu Nie, Huimin Ma
Biosensors and Bioelectronics 2013 Volume 49() pp:249-255
Publication Date(Web):15 November 2013
DOI:10.1016/j.bios.2013.05.019
•A facile and rapid method for the synthesis of l-proline-protected Au NCs was presented.•The prepared Au NCs was developed as the favorable probe for Fe3+ ion over other common cations.•The fluorescence assay is based on the aggregation-induced fluorescence quenching mechanism.•This proposed method was further successfully applied in the assay of serum iron.Gold nanoclusters (Au NCs) possess outstanding physical and chemical attributes that make them excellent scaffolds for the construction of novel chemical and biological sensors. In this study, a simple one-pot synthesis method, employing l-proline as the stabilizer, was presented for preparation of fluorescent Au NCs. This strategy allowed the generation of water-soluble Au NCs within a short time of 15 min. The as-prepared Au NCs exhibited a bluish fluorescence emission at 440 nm and a quantum yield of 2.94%. Based on the aggregation-induced fluorescence quenching mechanism, the Au NCs provided favorable biocompatibility, high sensitivity and good selectivity for the measurement of ferric ion (Fe3+). Furthermore, serum samples were analyzed for the serum iron contents by using this proposed biocompatible fluorescent sensor, indicating the potential value of this Au NCs-based fluorescent sensor for application in biological and clinical analysis.
Co-reporter:Juan Qiao, Li Qi, Ying Shen, Lingzhi Zhao, Cui Qi, Dihua Shangguan, Lanqun Mao and Yi Chen
Journal of Materials Chemistry A 2012 vol. 22(Issue 23) pp:11543-11549
Publication Date(Web):04 May 2012
DOI:10.1039/C2JM31093G
In this study, a novel fluorescent and temperature responsive block copolymer has been designed and synthesized by a reversible addition–fragmentation chain transfer (RAFT) polymerization method in terms of the strategy that N-isopropylacrylamide (NIPAm), maleic anhydride (MAn) and 7-amino-4-methylcoumarin (AMC) act as the temperature responsive unit, the hydrophilic unit and the fluorescent unit, respectively. The successfully synthesized block copolymer was characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance (1H NMR) spectroscopy. Meanwhile, the self-aggregation behaviour in aqueous solution and the thermo-responsive property of the block copolymer were demonstrated by particle size measurement, transmission electron microscopy (TEM) observations and lower critical solution temperature (LCST) determination, respectively. Then the variation of fluorescence intensity with temperature was confirmed. With increasing temperature, shrinking of PNIPAm chains caused the block copolymer to become more hydrophobic above the LCST, assembling larger aggregates with lower interfacial curvature. Thus a part of the fluorescent groups would be embedded inside the enlarged block copolymer micelles, resulting in lower fluorescence intensity. Furthermore, the superior hydrophilicity and biocompatibility of the block copolymer as a thermometer have been demonstrated by application in intracellular temperature sensing of MDCK cells ranging from 24 °C to 38 °C.
Co-reporter:Xiaoyu Mu, Li Qi, Ying Shen, Haizhi Zhang, Juan Qiao and Huimin Ma
Analyst 2012 vol. 137(Issue 18) pp:4235-4240
Publication Date(Web):03 Aug 2012
DOI:10.1039/C2AN35753D
A novel amino acid ionic liquid (AAIL) with L-ornithine (L-Orn) as anion was successfully synthesized, and subsequently applied as an available chiral ligand coordinated with Zn(II) in a chiral ligand exchange capillary electrophoresis (CLE-CE) system for the enantioseparation of dansyl amino acids (Dns-D,L-AAs). The influence of key parameters, such as buffer pH, concentration ratio of Zn(II) to ligand and complex concentration, was investigated in detail. Eleven pairs of Dns-D,L-AAs enantiomers were baseline separated and three pairs were partly separated under the optimum conditions. For exploring its potential application, the quantitative features of this proposed method were studied. Good linearity (r2 = 0.999) and favorable repeatability (RSD ≤ 3.4%) were obtained by using Dns-D,L-Met as the test analyte. Finally, this method was employed to investigate the inhibition efficiency of D-amino acid oxidase (DAAO) inhibitors, which may pave a new way for the high-throughput screening of enzyme inhibitors and relevant drug discovery.
Co-reporter:Haizhi Zhang;Lanqun Mao;Yi Chen
Journal of Separation Science 2012 Volume 35( Issue 10-11) pp:1236-1248
Publication Date(Web):
DOI:10.1002/jssc.201200067
Over the last couple of decades, researchers have developed diverse chiral separation methods emerged from a few chiral separation principles. This review article is primarily focused on the application of chiral ligand-exchange (CLE) principle in capillary electromigration techniques, such as capillary electrophoresis (CE) and capillary electrochromatography (CEC). First, the most commonly used CLE-CZE separation mode by using different kinds of central ions, such as Cu(II), Zn(II), borate ion, and other metal ions, has been introduced. Meanwhile, several kinds of surfactants have been applied as the micelle-forming agents in the CLE micellar electrokinetic chromatography mode. The highlight of recent research of CLE-CEC is the exploitation of novel columns for chiral separation. Then, two kinds of capillary columns, packed capillary and monolithic capillary column, have been briefly described. Finally, the effective application of these chiral separation methods has been presented, including the application in life science and food analysis area.
Co-reporter:Jun Yang;Yi Chen;Huimin Ma
Chinese Journal of Chemistry 2012 Volume 30( Issue 8) pp:1793-1796
Publication Date(Web):
DOI:10.1002/cjoc.201200357
Abstract
In this work, a 3D mixer has been conceived based on the splitting and recombining mechanism with simple topology structure. This mixer can present excellent performance at extremely low Reynolds number, which is very important for the practical use. Further research exhibits that the mixing also can be realized via the chaotic advection that occurred at decreased aspect ratio of channel. Thus, the changeable mechanism of mixer shows potential of being used widely. Meanwhile, mixing process has been confirmed in a fabricated structure. The simulated flow patterns reappear in a scaled-up mixer and full mixing can be achieved in 8 mm channel length at varied flow rate. Due to the high efficiency and easy fabrication, this 3D mixer possesses great prospect for a large number of microfluidic systems.
Co-reporter:Xiaoyu Mu, Li Qi, Juan Qiao, Haizhi Zhang, Huimin Ma
Analytical Biochemistry 2012 Volume 421(Issue 2) pp:499-505
Publication Date(Web):15 February 2012
DOI:10.1016/j.ab.2011.11.037
Alanine aminotransferase (ALT), which catalyzes the reversible conversion between l-glutamic acid (l-Glu) and l-alanine (l-Ala), is one of the most active aminotransferases in the clinical diagnosis of liver diseases. This work displays a microanalytical method for evaluating ALT enzyme kinetics using a microchip electrophoresis laser-induced fluorescence system. Four groups of amino acid (AA) mixtures, including the substrates of ALT (l-Glu and l-Ala), were effectively separated. Under the optimized conditions, the quantitative analysis of l-Glu and l-Ala was conducted and limits of detection (signal/noise = 3) for l-Glu and l-Ala were 4.0 × 10−7 and 2.0 × 10−7 M, respectively. In the reaction catalyzed by ALT, enzyme kinetic constants were determined for both the forward and reverse reactions by monitoring the concentration decrease of substrate AAs (l-Ala and l-Glu), and the Km and Vmax values were 10.12 mM and 0.48 mM/min for forward reaction and 3.22 mM and 0.22 mM/min for reverse reaction, respectively. Furthermore, the applicability of this assay was assessed by analysis of real serum samples. The results demonstrated that the proposed method could be used for kinetic study of ALT and shows great potential in the real application.
Co-reporter:Xiaoyu Mu, Li Qi, Haizhi Zhang, Ying Shen, Juan Qiao, Huimin Ma
Talanta 2012 Volume 97() pp:349-354
Publication Date(Web):15 August 2012
DOI:10.1016/j.talanta.2012.04.044
Ionic liquids (ILs) with l-proline (l-Pro) as cations have been developed for the novel chiral ligands coordinated with Cu(II) in chiral ligand exchange capillary electrophoresis (CLE-CE). Four kinds of amino acid ionic liquids (AAILs), including [l-Pro][CF3COO], [l-Pro][NO3], [l-Pro][BF4] and [l-Pro2][SO4], were successfully synthesized. Among them, [l-Pro][CF3COO] was selected as the model ligand to optimize the separation conditions. The influences of AAIL concentration, pH, and methanol concentration on efficiency of chiral separation were investigated. Then it has been testified that the optimal buffer solution consisted of 25.0 mM Cu(Ac)2, 50.0 mM AAIL and 20% (v/v) methanol at pH 4.0. The interesting thing is well enantioresolution could be observed with [l-Pro][CF3COO] as the new chiral ligand and nine pairs of labeled d,l-AAs were successfully separated with the resolution ranging from 0.93 to 6.72. Meanwhile, the baseline separation of labeled d,l-AAs could be achieved with the other three kinds of AAILs as ligands. The results have demonstrated the good applicability of AAILs with AAs as cations for chiral separation in CLE-CE system. In addition, comparative study was also conducted for exploring the mechanism of the AAILs as new ligands in CLE-CE.Highlights► AAILs with l-Pro as cations were explored as novel ligands in CLE-CE system. ► AAILs showed significant superiority over the common AA ligands in chiral separation by CLE-CE method. ► Discussion on the mechanism of AAILs as chiral ligands was presented.
Co-reporter:Ying Shen, Li Qi, Lanqun Mao
Polymer 2012 Volume 53(Issue 19) pp:4128-4134
Publication Date(Web):31 August 2012
DOI:10.1016/j.polymer.2012.07.019
Poly (glycidyl methacrylate) (PGMA) was successfully synthesized and proposed as a novel phase separator for fabrication of macroporous crosslinked poly (glycidyl methacrylate-co-ethylene dimethacrylate) (poly (GMA-co-EDMA)) monoliths with well-defined three dimensional (3D) skeletal structure. The ratio of PGMA in porogenic system had significant influence on morphology development of the monolith. To gain insight into the effect of PGMA chain length on morphology formation, PGMA homopolymers with different molecular weights were further synthesized for monolith preparation. Porous structure of the monoliths was characterized by scanning electron microscope, mercury intrusion porosimetry and gas absorption measurement. Additionally, the monoliths could maintain the well-defined 3D skeletal structure with a tunable amount of GMA monomer in polymerization system for improved permeability and functionality while the content of other components is fixed. Meanwhile, the successful application of the optimal monolith for separation of both small molecules and lager biomolecules was provided proof of its potential utilization in HPLC. Considering different requirements, the application of the novel well-defined 3D skeletal monolith could be easily widened via post-modification because of its possessing epoxy functionality. Hopefully, the newly synthesized PGMA with different molecular weights could be developed as a novel candidate polymeric phase separator for fabricating various monoliths with well-defined structure, comparable to commercially available ones.Graphical abstract
Co-reporter:Ying Shen ;Lingzhi Zhao ; Li Qi;Dr. Juan Qiao; Lanqun Mao; Yi Chen
Chemistry - A European Journal 2012 Volume 18( Issue 43) pp:13755-13761
Publication Date(Web):
DOI:10.1002/chem.201201993
Abstract
The development of magnetic nanoparticles with multiple functions has been an ever-growing field because of their diverse applications in drug delivery, biosensing, cell labeling, and so on. In this study, a facile method was developed to construct multifunctional magnetic nanocomposites. The approach is based on the use of poly(glycidyl methacrylate), PGMA, with numerous epoxy groups as reactive polymer to combine with fluorescent dye, the surface of magnetic nanoparticles, and targeting ligands directly without expatiatory functionality design. The resultant nanocomposites with good superparamagnetic and fluorescent properties could be exploited for bioimaging. Moreover, after conjugation with a model protein, namely, transferrin, which specifically targets cells overexpressing transferrin receptors, the nanocomposites could be used selectively to recognize Hela cells in comparison with nonconjugated ones. These results indicate that the newly designed magnetic nanocomposites with PGMA as functional polymer could serve as a novel versatile platform to conjugate with various molecules for construction of diverse multifunctional magnetic nanocomposites to meet different requirements and potential uses in nanomedicine and biological chemistry.
Co-reporter:Chunhe Yao, Li Qi, Wenbin Hu, Fuyi Wang, Gengliang Yang
Analytica Chimica Acta 2011 Volume 692(1–2) pp:131-137
Publication Date(Web):29 April 2011
DOI:10.1016/j.aca.2011.03.001
A new kind of immobilized trypsin reactor based on sub-micron skeletal polymer monolith has been developed. Covalent immobilization of trypsin on this support was performed using the epoxide functional groups in either a one- or a multi-step reaction. The proteolytic activity of the immobilized trypsin was measured by monitoring the formation of N-α-benzoyl-l-arginine (BA) which is the digestion product of a substrate N-α-benzoyl-l-arginine ethyl ester (BAEE). Results showed that the digestion speed was about 300 times faster than that performed in free solution. The performance of such an enzyme reactor was further demonstrated by digesting protein myoglobin. It has been found that the protein digestion could be achieved in 88 s at 30 °C, which is comparable to 24 h digestion in solution at 37 °C. Furthermore, the immobilized trypsin exhibits increased stability even after continuous use compared to that in free solution. The present monolithic enzyme-reactor provides a promising platform for the proteomic research.
Co-reporter:Haizhi Zhang, Li Qi, Juan Qiao, Lanqun Mao
Analytica Chimica Acta 2011 Volume 691(1–2) pp:103-109
Publication Date(Web):8 April 2011
DOI:10.1016/j.aca.2011.02.039
A novel quantitative approach for the determination of sodium benzoate (SB) was proposed by the kinetic study about its competitive inhibitory efficiency to d-amino acid oxidase (DAAO) activity with a chiral ligand exchange capillary electrophoresis (CE) method, in which the Zn(II)-l-prolinamide complex was chosen as a novel chiral selector. After the optimization of buffer pH and the chiral selector concentration this chiral ligand exchange CE method was employed to determine labeled d,l-Serine with good linearity (r2 ≥ 0.995), efficient recovery (95.6–100.9%) and remarkable reproducibility (RSD ≤ 1.2%). This chiral separation method was further used to observe DAAO activity through the determination of d-Serine concentration variation after being incubated with DAAO and obtain the sigmoidal inhibitory curve of SB to DAAO activity. The ascending part of this inhibitory curve was linearly fitted in a limited range for SB from 2.0 to 200 μM with an appropriate coefficient of determination (R2 = 0.990). The linearity was then validated to be a promising method for the analysis of SB with the standout merits of high selectivity and adjustable detection range. Furthermore, this proposed method was used for the pharmacokinetics study of SB.
Co-reporter:Juan Qiao, Li Qi, Xiaoyu Mu and Yi Chen
Analyst 2011 vol. 136(Issue 10) pp:2077-2083
Publication Date(Web):01 Apr 2011
DOI:10.1039/C1AN15067G
The study of enzyme immobilization using an extracorporeal shunt system is essential to eliminate the side effects of L-asparaginase (L-Asnase; including hepatic toxicity, allergic reaction, pancreatitis, central nervous system toxicity and decreased synthesis of blood clotting factors) when it was applied as an anticancer drug given directly to patients by injection. Thus, the novel monolith and coating enzymatic reactors of L-asparaginase were provided in this assay and a microchip electrophoresis–laser induced fluorescence (MCE–LIF) method was set up for the enzyme kinetics study. The enzymatic reactors would be a promising in vitro therapeutic method in an extracorporeal shunt system for acute lymphoblastic leukemia (ALL) treatment. For the first time, L-asparaginase was covalently bound to the polymer monolith and coating in the capillary and the activity characteristics of these enzymatic microreactors have been probed by Michaelis–Menten kinetic constants. Meanwhile, the D,L-amino acids were chirally separated using microchip electrophoresis with a laser induced detector and D,L-aspartic acid (D,L-Asp) were tested for the L-asparaginase enzymatic reactor kinetics study. Furthermore, human serum adding with L-asparagine (L-Asn) as the sample was hydrolyzed by the enzymatic microreactors. The results demonstrated that the developed enzymatic microreactor of L-asparaginase would be a potential therapeutic protocol for ALL treatment.
Co-reporter:Ying Shen;Jianglei Qin;Haizhi Zhang;Juan Qiao;Yongming Chen;Lanqun Mao
Journal of Separation Science 2011 Volume 34( Issue 24) pp:3538-3545
Publication Date(Web):
DOI:10.1002/jssc.201100049
Abstract
Exposure to aromatic amines from different industrial and agricultural activities entails a substantial risk of deleterious somatic effects, genetic damage and cancer development. Thus, a new and simple method for separation and analysis of aromatic amines has been developed by open-tubular capillary electrochromatography with a novel amphipathic block copolymer (poly(tert-butyl acrylate)127-block-poly(glycidyl methacrylate)86) coating based on its self-assembled property. Key factors affecting the separation efficiency of the test analytes, such as pH, buffer concentration and selective solvent, were studied in detail. Meanwhile, method validation was well evaluated by linearity (≥0.998), detection limit and recovery. Application of this developed protocol on in vitro monitoring of the target aromatic amines distribution in rat blood demonstrated its potential usage for separation and determination of aromatic amines in biological samples. Additionally, for assimilating more polymeric materials into analysis of aromatic amines, the effect of morphology changes of the amphipathic block copolymer coating on open-tubular capillary electrochromatography separation was also studied, and the result revealed that the block copolymer coating could play the same role as surfactant.
Co-reporter:Jun Yang;Juan Qiao;Yi Chen;Huimin Ma
Chinese Journal of Chemistry 2011 Volume 29( Issue 11) pp:2385-2388
Publication Date(Web):
DOI:10.1002/cjoc.201180407
Abstract
Based on microreactors, the representative Baylis-Hillman reaction of cyclopent-2-enone coupled with 4-nitrobenzaldehyde in the presence of imidazole could be accelerated by manipulating the temperature and electric field. Furthermore, the electric field was used in promoting Baylis-Hillman reaction for the first time with the rate acceleration approximately 5.2-fold higher than that carried out in conventional vessels as well as 4.0-fold under control of temperature. Meanwhile, the products of Baylis-Hillman reaction at every time point could be collected and then determined by capillary micellar electrokinetic chromatography.
Co-reporter:Ying Shen, Li Qi, Xiaoyi Wei, Rongyue Zhang, Lanqun Mao
Polymer 2011 Volume 52(Issue 17) pp:3725-3731
Publication Date(Web):3 August 2011
DOI:10.1016/j.polymer.2011.06.041
Well-defined poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA) brushes were successfully prepared on the monolithic surface via two-step atom transfer radical polymerization (ATRP). The polymer brushes synthesized by the second-step ATRP were based on the active bromic groups resulting from poly (ethylene glycol dimethacrylate) (pEDMA) monolith which was prepared at room temperature by the first-step ATRP. Element analysis was used to monitor the grafting process at different reaction times. Each step of preparation was characterized by scanning electron microscope, infrared spectrum and mercury intrusion porosimetry. Employment of PDMAEMA grafted monolith as the stationary phase for chromatographic analysis of steroids demonstrated that the PDMAEMA brushes possessed both pH- and salt-responsive properties. Noticeably, it has been found that the chain length of PDMAEMA brushes could influence the retention behavior of steroids due to the controllability of ATRP, which proposed an interesting alternative to modulate retention in HPLC. This is the first application of PDMAEMA brushes grafted monolith by two-step ATRP method for constructing responsive surface in HPLC and it might exploit a new path for widening the monolith application in various fields.
Co-reporter:Ying Shen, Li Qi, Jianglei Qin, Huijuan Yan, Juan Qiao, Haizhi Zhang, Yongming Chen, Lanqun Mao, Lijun Wan
Talanta 2011 Volume 84(Issue 2) pp:501-507
Publication Date(Web):15 April 2011
DOI:10.1016/j.talanta.2011.01.039
A new amphipathic block copolymer, poly(tert-butyl acrylate)127-block-poly(glycidyl methacrylate)86, was developed for the coating in open tubular capillary electrochromatography. The self-assembly characters of the coating, which could form micelle-like aggregates under proper conditions, were observed by atomic force microscopy. Compared with bare capillary, this coating could act as surfactant and lead to improve the separation of steroids. In addition, the influence of pH, buffer concentration and organic solvents on the separation was investigated. The best separation of the three model steroid analytes could be achieved using 20.0 mM borate buffer at pH 10.5. For covalent bonding, the coating showed good repeatability and stability with RSD of uEOF less than 3.3%. Then, this proposed method was well validated with good linearity (≥0.999), recovery (91.0–94.0%) and repeatability, and was successfully used for separation of steroids in spiked serum samples, which indicated that this new OT-CEC method could provide a potential tool to determine steroids in real biological system without interference.
Co-reporter:Peiyong Xin, Ying Shen, Li Qi, Gengliang Yang, Yi Chen
Talanta 2011 Volume 85(Issue 2) pp:1180-1186
Publication Date(Web):15 August 2011
DOI:10.1016/j.talanta.2011.05.037
A novel type of poly(N-isopropylacrylamide) grafted E-51 epoxy-based monoliths in a 100 mm × 4.6 mm I.D. stainless steel column with well-controlled three-dimensional skeletal structures has been prepared and proposed for the separation of proteins. The grafted PNIPAAm chain via surface-initiated atom transfer radical polymerization was successfully performed. The proposed method provided a new route to modify the E-51 epoxy-based monoliths for widening their applications. Meanwhile, the temperature and the salt concentration responses of the grafted monolithic columns were investigated. Under the salt gradient, six proteins were well separated in hydrophobic interaction mode. Moreover, for further confirming the application of the prepared monolith was meaningful for proteome analysis in actual system, the separation of human serum sample was performed.
Co-reporter:Xiaoyi Wei, Li Qi, Junjun Tan, Ruigang Liu, Fuyi Wang
Analytica Chimica Acta 2010 Volume 671(1–2) pp:80-84
Publication Date(Web):25 June 2010
DOI:10.1016/j.aca.2010.05.006
A simple and sensitive colorimetric method for cysteine detection was established based on the carboxymethyl cellulose-functionalized gold nanoparticles (CMC-AuNPs). The nanoparticles were directly synthesized with sodium carboxymethyl cellulose by a simple approach, which would protect particles against salt-induced aggregation. Then the CMC-AuNPs solution exhibited a high colorimetric selectivity to cysteine. The assay results indicated that the introduction of cysteine could induce the aggregation of the colloidal solutions at the presence of sodium chloride, displaying changes in color and in UV–vis absorption spectra. Thus an exceptionally simple, rapid method for detecting cysteine was obtained at the linear range of 10.0–100.0 μM with the relative coefficient of 0.997. The proposed method possessed the advantages of simplicity and sensitivity, and was applied to real urine sample detection. The results were satisfying and the proposed method was especially appropriate for detection of cysteine in biological samples.
Co-reporter:Chunhe Yao;Gengliang Yang;Fuyi Wang
Journal of Separation Science 2010 Volume 33( Issue 4-5) pp:475-483
Publication Date(Web):
DOI:10.1002/jssc.200900655
Abstract
A novel kind of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate)-based monolithic column was developed for LC by directing supramolecular self-assembly of high internal phase emulsion. Mercury intrusion porosimetry characterization and scanning electron microscope pictures showed that these monoliths presented micrometer-sized throughpores, unique sub-micron skeletons and relatively large specific surface area. Additionally, porosity of monoliths could be adjusted while skeletons remained in the size range of 100.0–1000.0 nm. The new monoliths demonstrated not only better column efficiency, but also larger binding capacity. Dynamic binding capacity for protein (BSA) was evaluated to be 42.5 mg/mL, above two times higher than that of the general monoliths (19.1 mg/mL) and higher than that of commercial “Convective Interaction Media” monolithic columns (30.0 mg/mL). Moreover, their chromatographic behaviors were also evaluated in detail by chemical stability and swelling characterization of the monolithic column. Separation of proteins mixture (cytochrome c, myoglobin, ribonuclease A, lysozyme and BSA) on the monolith was achieved within 4 min at velocity of 1440.0 cm/h. Those unique properties made the novel monolithic column a promising alternative to commercially available monolithic supports in LC applications.
Co-reporter:Chunhe Yao, Li Qi, Juan Qiao, Haizhi Zhang, Fuyi Wang, Yi Chen, Gengliang Yang
Talanta 2010 Volume 82(Issue 4) pp:1332-1337
Publication Date(Web):15 September 2010
DOI:10.1016/j.talanta.2010.06.041
A new kind of immobilized human serum albumin (HSA) column was developed by using the sub-micron skeletal polymer monolith based on poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [poly(GMA-EDMA)] as the support of high-performance affinity chromatography. Using the epoxide functional groups presented in GMA, the HSA immobilization procedure was performed by two different means. The affinity columns were successfully adopted for the chiral separation of d,l-amino acids (AAs). Then this method was shown to be applicable to the quantitative analysis of d-tryptophan, with a linear range between 12.0 μM and 979.0 μM, and a correlation coefficient above 0.99. Furthermore, it was used for the analysis of urine sample. This assay is demonstrated to be facile and relatively rapid. So it allows us to measure the enzyme catalytic activity in the incubation of d,l-AAs with d-AA oxidase and to study the kinetics of the enzyme reaction. It implied that the affinity monolithic columns can be a useful tool for studying DAAO enzyme reaction and investigating the potential enzyme mechanism requirement among chiral conversion.
Co-reporter:Rongyue Zhang, Li Qi, Peiyong Xin, Gengliang Yang, Yi Chen
Polymer 2010 Volume 51(Issue 8) pp:1703-1708
Publication Date(Web):6 April 2010
DOI:10.1016/j.polymer.2010.02.002
A three diamensional (3D) bicontinuous skeleton macroporous monolith was firstly prepared by in situ atom transfer radical polymerization (ATRP) of ethylene glycol dimethacrylate (EDMA) at the room temperature. The structure of the monolith could be mediated by the different ratio of EDMA to initiator and the 3D bicontinuous skeleton structure was obtained at the ratio of 70:1. Compared with the traditional monoliths prepared by conventional free radical polymerization, the monolith made of ATRP could be trended to form the 3D bicontinuous skeleton macroporous structure, due to low concentration of free radical and the step-wise growth of polymer chains in ATRP. The diameter of the monolith could be enlarged to 50 mm without obvious volume shrink and cracks in the body. The morphology and pore distribution of the monolith were characterized by SEM and mercury intrusion porosimetry. The monolith was modified by grafting polymerization of n-butyl methacrylate, and then the grafted monolith was used to separate some steroids and proteins by reversed-phase liquid chromatography.
Co-reporter:Peiyong Xin, Li Qi, Rongyue Zhang, Chunhe Yao, Xiaoyi Wei, Gengliang Yang, Yi Chen
Polymer 2010 Volume 51(Issue 15) pp:3410-3415
Publication Date(Web):8 July 2010
DOI:10.1016/j.polymer.2010.05.043
A novel type of amphiphilic diblock copolymer consisting of butyl methacrylate (BMA) block and glycidyl methacrylate (GMA) block (BG copolymer) was successfully synthesized via atom transfer radical polymerization (ATRP) and then utilized as a phase separator to control the porous structure of poly(butyl methacrylate-co-ethylene dimethacrylate) (poly(BMA-co-EDMA)) monoliths. It has been found that the addition of the BG copolymer had a great impact on the polymerization of the monoliths. When the amount of the BG copolymer added into the synthesizing solution was changed, the porous structure could be varied from aggregated microglobular structure to well-defined three-dimensional (3D) skeletal structure. The porous structure was characterized by scanning electron microscope, mercury intrusion porosimetry and nitrogen adsorption measurement. Finally, the separation of proteins demonstrated its potential applications in proteome research.
Co-reporter:Li Qi, Gengliang Yang, Haizhi Zhang, Juan Qiao
Talanta 2010 Volume 81(4–5) pp:1554-1559
Publication Date(Web):15 June 2010
DOI:10.1016/j.talanta.2010.03.001
A new strategy for the enantioseparation of d,l-amino acids employing the principle of ligand exchange capillary electrophoresis with Zn(II)–l-valine complex as a chiral selecting system in the presence of β-cyclodextrin has been designed. Successful enantioseparation of label free and labeled amino acids have been achieved with a buffer of 100.0 mM boric acid, 5.0 mM ammonium acetate, 4.0 mM β-cyclodextrin, 4.0 mM ZnSO4 and 8.0 mM l-valine at pH 8.1. This new method was shown to be applicable to the quantitative analysis of label free d- and l-aromatic amino acids. Furthermore, the expanding enzymatic use of l-amino acid oxidase to incubate with different l-amino acids has allowed understanding of the substrate's specificity. An on-column incubation assay has been developed to study the l-amino acid oxidase's catalytic efficiency. It was demonstrated that the enzyme kinetic constant could be determined by using this new method.
Co-reporter:Chunhe Yao, Li Qi, Hongying Jia, Peiyong Xin, Gengliang Yang and Yi Chen
Journal of Materials Chemistry A 2009 vol. 19(Issue 6) pp:767-772
Publication Date(Web):17 Dec 2008
DOI:10.1039/B816712E
A series of glycidyl methacrylate-based polymer monoliths, including spherical walled structures, sub-micron skeletons, and lamellar morphologies, are reproducibly prepared by high internal phase emulsions in combination with block copolymer chemistry. The morphologies could be manipulated over a wide range by only altering the typical tri-block copolymer (Pluronic F127) concentration. The ability of the Pluronic F127 to direct supramolecular self-assembly is the main reason for the rich phase behavior exhibited such as the micellar phase (i.e., spherical micelles, wormlike micelles), the bicontinuous phase, and the lamellar phase. Equally important, the glycidyl methacrylate-based monoliths differ significantly from conventional polymer monoliths; they have sub-micron skeletons (100–1000 nm), micrometer-sized throughpores, relatively large specific surface area (161 m2 g−1), and excellent permeability (6.1 × 10−13 m2). Further, the monoliths display superiority in fast and high-throughput separation of proteins. This, together with easy fabrication makes the novel monoliths a promising alternative to commercially available monolithic supports.
Co-reporter:Rongyue Zhang, Gengliang Yang, Peiyong Xin, Li Qi, Yi Chen
Journal of Chromatography A 2009 Volume 1216(Issue 12) pp:2404-2411
Publication Date(Web):20 March 2009
DOI:10.1016/j.chroma.2009.01.023
Poly(N-isopropylacrylamide)-grafted polymer monolith has been achieved using a surface-initiated atom transfer radical polymerization grafting polymerization within the pores of poly(chloromethylstyrene-divinylbenzene) macroporous monolith contained in a 100 mm × 4.6 mm I.D. stainless steel column. The grafted-poly(N-isopropylacrylamide) on the surface of the grafted monolith that was used as chromatographic stationary phase showed a response to the variation of temperatures and/or salt concentrations. This study focus on its salt concentration responsive property and it has been revealed that the hydrophobicity of the grafted monolith can be adjusted by changing salt concentrations in the range of 0.05–2.0 mol/L. A variety of salts including sodium sulfate, ammonium sulfate and sodium chloride exhibited different effects on the alteration of hydrophobicity of the grafted monolith, and the effect of the salts was in the order of sodium sulfate > ammonium sulfate > sodium chloride. Based on this response to salt concentrations, the grafted monolith was applied in hydrophobic interaction chromatography of proteins, and the base-line separation of a six proteins mixture consisting of cytochrome c, myoglobin, ribonuclease A, bovine serum albumin, ovalbumin and thyroglobulin bovine was achieved by a salt gradient elution.
Co-reporter:Li Qi;Kai Cui;Juan Qiao;Gengliang Yang;Yi Chen
Journal of Separation Science 2009 Volume 32( Issue 9) pp:1480-1486
Publication Date(Web):
DOI:10.1002/jssc.200800612
Abstract
A facile, fast and high efficiency micellar EKC has been explored for the analysis and UV detection of p-nitrobenzaldehyde and 2-[hydroxy(4-nitrophenyl)methyl]-2-cyclopenten-1-one with a buffer electrolyte of 30.0 mM tetraborate and 50.0 mM sodium taurodeoxycholate at pH 9.3. Under the optimal conditions, a linear range from 7.8×10–2 to 5.0×102 mM for those analytes (r2 > 0.99) was achieved. The LOD was 3.9 μM for 2-[hydroxy(4-nitrophenyl)methyl]-2-cyclopenten-1-one and 7.8 μM for p-nitrobenzaldehyde, respectively (S/N = 3). The applicability of this new method for the analysis of reactants (p-nitrobenzaldehyde and cyclopent-2-enone), catalysts (imidazole or N-methyl imidazole or 1-benzyl-imidazole) and product (2-[hydroxy(4-nitrophenyl)methyl]-2-cyclopenten-1-one) on offline Baylis–Hillman reaction was examined. The relationship between the reaction time and the amount of product has been studied. Meanwhile, three different kinds of catalysts were investigated for getting the desired moderate to good amount products. It was found that comparing with N-methyl imidazole or 1-benzyl-imidazole catalyst, imidazole-catalyzed reaction could produce more products within the same reaction time. Furthermore, the results indicated that the rate law for the investigated Baylis–Hillman reaction was second-order reaction. The rate constant for the reaction is 1.34 (±0.01)×10–3 mol–1 m3/s.
Co-reporter:Juan Qiao;Huimin Ma
Journal of Separation Science 2009 Volume 32( Issue 22) pp:3936-3944
Publication Date(Web):
DOI:10.1002/jssc.200900527
Abstract
A new type of block copolymer, which was synthesized by styrene and maleic anhydride, P(MAn-alt-St)119-b-PSt558, was successfully developed as the capillary coatings in open tubular CEC. It is interesting that the covalently bonded coatings are porous and the coatings can play the role of surfactants in the separation of aromatic amines when the buffer solution was composed of 30.0 mM ammonium acetate at pH 7.7 with 20% THF. Thus, successful baseline separation of five kinds of aromatic amines has been achieved. As validated by both artificially prepared solutions of aromatic amines and four real samples of commercially available permanent hair dyes, this proposed method was successfully applicable to the quantitative analysis of p-phenylenediamine (PPD) and o-phenylenediamine (OPD) ingredients in these commercial products, with a linear range between 8.3 μM and 6.0 mM, correlation coefficient above 0.990 and recovery between 83.5 and 110.9%. The detection limit obtained from calculations based on signal-to-noise ratio (S/N=3) was 4.2 μM for PPD and 6.0 μM for OPD, respectively. Furthermore, the role of the surfactants played by the block copolymer coatings has been primarily explored.
Co-reporter:Rongyue Zhang;Qin Xiao;Peiyong Xin;Gengliang Yang
Chinese Journal of Chemistry 2009 Volume 27( Issue 11) pp:2229-2236
Publication Date(Web):
DOI:10.1002/cjoc.200990374
Abstract
A new temperature-responsive porous monolith has been prepared by surface-initiated activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) grafting poly(N-isopropylacrylamide) (PNIPAAm) within the pores of the porous polymer monolith. The grafting copolymerization was carried out by a method based on a continuous flow-through technique without special deoxygenation procedure needed in the general ATRP. The addition of ascorbic acid could counteract the oxidation effect of oxygen diffusing into the reaction system. The resulting grafted monolith was characterized by a mercury intrusion method and the size of macropore was 3.65 µm, which was suitable for flow through the monolith for HPLC. The thermally responsive property of the grafted monolith was evaluated by HPLC using steroids with various hydrophobicities as probes. Through determination of retention factor of each steroid on the grafted monolith at different temperatures using water as mobile phase, it was found that the slope of the plot of retention factor of each steroid versus the temperature changed around the low critical solution temperature (LCST, 32°C) of PNIPAAm in water. It was relative to the grafted PNIPAAm temperature sensitivity that a hydrophobic and hydrophilic alternation would take place around its LCST. Based on this thermally responsive property, the grafted monolith was used as stationary phase for HPLC and to separate the steroids using water as mobile phase by changing the column temperature. As a mobile phase, water is much better than organic solvents concerning the environment.
Co-reporter:Juan Qiao, Li Qi, Huimin Ma, Huwei Liu, Jun Yang, Yi Chen, Gengliang Yang
Talanta 2009 Volume 80(Issue 2) pp:770-776
Publication Date(Web):15 December 2009
DOI:10.1016/j.talanta.2009.07.056
An innovative block copolymer capillary coating P(MAn-alt-St)127-b-PSt592, synthesized by maleic anhydride and styrene, was developed as a new kind of coating for capillary electrophoresis. The covalent bond coating was effectively applied in the separation of raw material (4-nitrobenzaldehyde) and production (2-[hydroxy(4-nitrophenyl)methyl]-cyclopent-2-enone) in a Baylis–Hillman reaction using ammonium acetate with 20% tetrahydrofuran (v/v) as the buffer solution. Electroosmotic flow measurement gave an instantly stable value after 70 times continued injection in 5 days and showed that P(MAn-alt-St)127-b-PSt592 coatings could suppress electroosmotic flow effectively compared with the bare capillary. The effects of tetrahydrofuran and the pH of buffer on the separation were investigated. The characteristics of the coatings to form micelles similar to surfactants were detected by atomic force microscopy. Moreover, the superiority of this coating was further applied in the separation of four aromatic amines.
Co-reporter:Xiaoyi Wei, Li Qi, Gengliang Yang, Fuyi Wang
Talanta 2009 Volume 79(Issue 3) pp:739-745
Publication Date(Web):15 August 2009
DOI:10.1016/j.talanta.2009.04.062
A novel modified monolithic column with pH-responsive polymer chains was prepared by grafting methacrylic acid onto the poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith. The grafting polymerization was achieved in an in situ manner which was performed by pumping methacrylic acid directly through an acidic hydrolysis monolithic column using potassium peroxydisulfate initiated free-radical polymerization. The grafted monolithic column was demonstrated to be the pH-responsive to the pore structure and the chromatographic characterization. The permeability of the column and the retention factors of five benzene homologues decreased due to the conformational changes of the polymer chains when the pH of mobile phase increased from 4.5 to 7.5. Furthermore, the modified monolithic column was used as the pH-responsive stationary phase and exhibited an excellent separation of four basic proteins.
Co-reporter:Juan Qiao, Li Qi, Ying Shen, Lingzhi Zhao, Cui Qi, Dihua Shangguan, Lanqun Mao and Yi Chen
Journal of Materials Chemistry A 2012 - vol. 22(Issue 23) pp:NaN11549-11549
Publication Date(Web):2012/05/04
DOI:10.1039/C2JM31093G
In this study, a novel fluorescent and temperature responsive block copolymer has been designed and synthesized by a reversible addition–fragmentation chain transfer (RAFT) polymerization method in terms of the strategy that N-isopropylacrylamide (NIPAm), maleic anhydride (MAn) and 7-amino-4-methylcoumarin (AMC) act as the temperature responsive unit, the hydrophilic unit and the fluorescent unit, respectively. The successfully synthesized block copolymer was characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance (1H NMR) spectroscopy. Meanwhile, the self-aggregation behaviour in aqueous solution and the thermo-responsive property of the block copolymer were demonstrated by particle size measurement, transmission electron microscopy (TEM) observations and lower critical solution temperature (LCST) determination, respectively. Then the variation of fluorescence intensity with temperature was confirmed. With increasing temperature, shrinking of PNIPAm chains caused the block copolymer to become more hydrophobic above the LCST, assembling larger aggregates with lower interfacial curvature. Thus a part of the fluorescent groups would be embedded inside the enlarged block copolymer micelles, resulting in lower fluorescence intensity. Furthermore, the superior hydrophilicity and biocompatibility of the block copolymer as a thermometer have been demonstrated by application in intracellular temperature sensing of MDCK cells ranging from 24 °C to 38 °C.
Co-reporter:Chunhe Yao, Li Qi, Hongying Jia, Peiyong Xin, Gengliang Yang and Yi Chen
Journal of Materials Chemistry A 2009 - vol. 19(Issue 6) pp:NaN772-772
Publication Date(Web):2008/12/17
DOI:10.1039/B816712E
A series of glycidyl methacrylate-based polymer monoliths, including spherical walled structures, sub-micron skeletons, and lamellar morphologies, are reproducibly prepared by high internal phase emulsions in combination with block copolymer chemistry. The morphologies could be manipulated over a wide range by only altering the typical tri-block copolymer (Pluronic F127) concentration. The ability of the Pluronic F127 to direct supramolecular self-assembly is the main reason for the rich phase behavior exhibited such as the micellar phase (i.e., spherical micelles, wormlike micelles), the bicontinuous phase, and the lamellar phase. Equally important, the glycidyl methacrylate-based monoliths differ significantly from conventional polymer monoliths; they have sub-micron skeletons (100–1000 nm), micrometer-sized throughpores, relatively large specific surface area (161 m2 g−1), and excellent permeability (6.1 × 10−13 m2). Further, the monoliths display superiority in fast and high-throughput separation of proteins. This, together with easy fabrication makes the novel monoliths a promising alternative to commercially available monolithic supports.
Co-reporter:Juan Qiao, Xiaoyu Mu, Li Qi, Jingjing Deng and Lanqun Mao
Chemical Communications 2013 - vol. 49(Issue 73) pp:NaN8032-8032
Publication Date(Web):2013/07/05
DOI:10.1039/C3CC44256J
A novel nano-conjugate containing ultrasmall water-soluble AuNCs protected by ovalbumin as the fluorescent part, folic acid as the targeting ligand and a homopolymer N-acryloxysuccinimide as the linker has been investigated. Moreover, specific staining of HeLa cells by the nano-conjugate has been demonstrated.
Co-reporter:Juan Qiao, Chuanfang Chen, Li Qi, Meirong Liu, Ping Dong, Qin Jiang, Xinzheng Yang, Xiaoyu Mu and Lanqun Mao
Journal of Materials Chemistry A 2014 - vol. 2(Issue 43) pp:NaN7550-7550
Publication Date(Web):2014/09/08
DOI:10.1039/C4TB01154F
Intracellular temperature imaging could help to understand diverse biological reactions and functions in living cells. Herein, we report a nanothermometer based on ratiometric fluorescent polymers (RFPs) synthesized by the living/controlled reversible addition–fragmentation transfer polymerization method for intracellular temperature sensing. The thermometer was composed of a thermo sensitive polymer, a polarity sensitive fluorescent dye and a thermo insensitive fluorescent dye. With the increasing temperature, the fluorescent intensity of RFPs increased because of the fluorescent intensity enhancement of the polarity sensitive fluorescent dye induced by the self assembling of the thermo sensitive polymer. The prepared RFPs exhibited a fluorescence “turn-on” response at higher temperature. We further investigated the simultaneous temperature sensing and the ratiometric imaging of temperature variations associated with biological processes in living cells using this novel ratiometric probe. The polymer based ratiometric fluorescent thermometer can be used to precisely measure the temperature in living cells, and shows great potential in spatio-temporal temperature sensing down to the nanoscale within biological systems.
Co-reporter:Ying Shen, Wei Guo, Li Qi, Juan Qiao, Fuyi Wang and Lanqun Mao
Journal of Materials Chemistry A 2013 - vol. 1(Issue 17) pp:NaN2267-2267
Publication Date(Web):2013/02/25
DOI:10.1039/C3TB20116C
The effort to stabilize enzymes and improve their activity has generated great interest because of their wide application in proteomics research, bioenergy conversion, bioassays and so on. In this work, biocompatible reactive polymer, poly (glycidyl methacrylate), grafted from magnetic nanoparticles by atom transfer radical polymerization method, has been firstly proposed to immobilize enzymes for microwave-assisted digestion. Meanwhile, trypsin was chosen as a model enzyme. Resulting from the increased functionality, the immobilization amount of the enzyme on the magnetic nanoparticle surface has been greatly improved. Furthermore, the enzyme immobilized magnetic nanoparticles have exhibited excellent repeatability and stability. The influence of the polymer chain length on digestion efficiency has been investigated both at 37 °C and under microwave. It has been found that the digestion efficiency increases with the lengthened polymer brushes due to the increased immobilization amount. Utilizing cytochrome C as a model protein for digestion, the performance of this immobilized biocatalyst has been demonstrated and this digestion assisted with microwave could be completed within 15 s. This study offers insight into the design of polymer brushes on the surface of magnetic nanoparticles for high digestion efficiency in the future.
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 23) pp:NaN9911-9911
Publication Date(Web):2015/10/21
DOI:10.1039/C5AY02483H
A facile and green strategy has been developed for the in situ synthesis of polyacrylamide (PAM)-protected gold nanoparticles (AuNPs). A PAM polymer with thiol-terminated groups was prepared using the reversible addition–fragmentation chain transfer radical polymerization method. The PAM with thiol-terminated groups was able to capture gold ions to form PAM-AuNPs, which displayed a specific response to manganese ions in aqueous solution. The binding forces between the PAM and the manganese ions caused the PAM-AuNPs to move closer together, decreasing the interparticle distance and forming aggregates with a small red shift in the UV-visible absorption band. Dynamic light scattering analysis showed an obviously increased surface charge for the PAM-AuNPs when they were exposed to manganese ions, which could cause cross-linking aggregation. The PAM-AuNPs were used for the determination of manganese ions in the linear range 8.0–500 μmol L−1 with a limit of detection of 5.0 μmol L−1. These aggregates therefore provide a promising assay for the determination of manganese ions in real water samples.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 16) pp:
Publication Date(Web):
DOI:10.1039/C4AY01137F
The simplicity of the one-pot green synthesis routine and the capability of surface modification of various bioactive molecules make gold nanoclusters (Au NCs) highly suitable as scaffolds for the construction of novel chemical and biological sensors. In this work, we report a novel strategy to prepare amino acid stabilized fluorescent Au NCs via a green one-pot process. The obtained Au NCs possessed light green fluorescence with maximum emission at 498 nm and their quantum yield (QY) was evaluated to be 1.68%. Subsequently, the developed fluorescent Au NC biosensor allowed sensitive and selective detection of Fe3+ ions based on fluorescence quenching with a detection limit of 0.2 μM and Al3+ ions based on enhanced fluorescence with a detection limit of 0.3 μM, respectively. Furthermore, we testified the feasibility of applying this fluorescent probe for real sample analysis through the detection of Al3+ ions and Fe3+ ions in lake water, pond water and tap water. These results indicated that the as-prepared Au NCs had great potential to be developed as the favorable sensor for detection of metal ions in real samples.
Co-reporter:Juan Qiao, Xiaoyu Mu and Li Qi
Journal of Materials Chemistry A 2013 - vol. 1(Issue 42) pp:NaN5761-5761
Publication Date(Web):2013/09/19
DOI:10.1039/C3TB21169J
In this work, we present a facile in situ strategy for synthesis of thermo-responsive gold nanoparticles (GNPs) at room temperature. By using the RAFT polymerization methods, thermo-responsive polymer chains possessing trithiocarbonate groups have been synthesized which can be split into two chains and can produce a thiol end-group by NaOH. Then the thiol end-group polymer chains can act as anchors to capture the Au(III) ions in aqueous solution to form thermo-responsive GNPs. The thermo-responsive GNPs synthesized by the proposed method exhibited a reversible, clear–opaque transition in solution between 35 °C and 60 °C. It is conjectured that this strategy possesses the virtues including in situ, “green”, universal and tailored without a tedious reducing procedure using any toxic reducing agents. Further, the thermo-responsive GNPs have been applied for the effective analysis of cysteine in urine samples.
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