Qing Dai

Huazhong University of Science and Technology, Wuhan, Hubei, China

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Publications (6)26.26 Total impact

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    ABSTRACT: A rapid, sensitive and selective electrochemical method was proposed for the determination of 2,4-dinitrophenol (2,4-DNP) in surface water samples, using hydrophilic molecular imprinted polymers (MIPs) as the recognition element and nickel (Ni) fiber as the catalytic element. Hydrophilic MIPs were synthesized using 2,4-DNP as the template, acrylamide as the monomer, glycidilmethacrylate as the pro-hydrophilic co-monomer and acetonitrile as the solvent. Hydrophilic modification could enhance the accessibility of 2,4-DNP to the imprinted cavities and improve the selective recognition properties of traditional MIPs in water medium. Subsequently, hydrophilic MIPs/Ni fiber electrode was prepared to determine trace 2,4-DNP by cyclic voltammetry. The parameters affecting the analytical performance were investigated. Under optimized conditions, the linear range was 0.7-30 μg L⁻¹ and the detection limit was 0.1 μg L⁻¹. Finally, the proposed method was applied to measure 2,4-DNP in surface water samples. The spiked recoveries were changed from 91.3% to 102.6% and the RSD was not higher than 5.1%. There was no statistically significant difference between the results obtained by the proposed method and the traditional chromatographic method.
    Biosensors & Bioelectronics 07/2011; 26(11):4450-6. · 6.45 Impact Factor
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    ABSTRACT: An automated system has been developed for the determination of trace tetracycline antibiotics (TCs) in egg samples, based on online molecularly imprinted solid-phase extraction (MISPE) coupling with high-performance liquid chromatography (HPLC). Oxytetracycline and chlortetracycline were chosen as mixed templates to synthesize highly selective molecularly imprinted polymers for online extraction. Under the optimal online MISPE-HPLC condition, 10 mL egg samples were injected into the MISPE column and then the matrix was washed out. By rotating the switching valve, TCs were transferred to the analytical column and then separated by HPLC. Because sample pretreatment and chromatographic separation were carried out simultaneously, the whole analytical time (18 min) was significantly shortened compared with conventional offline techniques. The detection limits ranged from 0.8 to 1.3 ng/g. The enhancement factors were in the range of 159-410. The spiked recoveries of TCs in real egg samples ranged from 91.6 to 107.6% and the relative standard deviations (RSDs) were not higher than 4.0%.
    Journal of Separation Science 06/2011; 34(12):1469-76. · 2.59 Impact Factor
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    ABSTRACT: A rapid, low cost and selective chemiluminescence method coupled with magnetic molecularly imprinted polymers extraction was developed to detect lysozyme in human urine samples. Compared with traditional solid-phase extraction, this method could achieve selective extraction for the lysozyme, avoid the time consuming elution from a column or centrifugation steps, and then showed great potential in the high-throughput screening of clinical samples. The parameters affecting the performance of extraction and chemiluminescence were investigated. Under optimal conditions, the whole analytical procedure was completed within 12 min and spiked recovery ranged from 90.1% to 103.7% (R.S.D.≤6.7%). The limit of quantitation was 5 ng mL(-1). Furthermore, the results obtained by the proposed method were linearly correlated to those by commercial lysozyme detection kit (r=0.9595). Finally, the validated method was used to measure the urinary lysozyme of renal disease patients and healthy controls. The results confirmed the reliability and practicality of the protocol and revealed a good perspective of this method for biological sample analysis.
    Analytica chimica acta 04/2011; 692(1-2):73-9. · 4.31 Impact Factor
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    ABSTRACT: Molecular imprinting is an attractive technique for preparing mimics of natural, biological receptors. Nevertheless, the imprinting of macromolecule remains a challenge due to their bulkiness and sensitivity to denaturation. In this work, we presented a method for preparing multifunctional lysozyme-imprinted nanoparticles (magnetic susceptibility, molecular recognition and environmental response). The magnetic susceptibility was imparted through the successful encapsulation of Fe3O4 nanoparticles. Selective lysozyme recognition depended on molecularly imprinted film. Moreover, it was also a hydrophilic stimuli-responsive polymer, which could undergo a reversible change of imprinted cavity in response to a small change in the environmental conditions. Thus, magnetic molecularly imprinted nanoparticles had high adsorption capacity (0.11 mg mg(-1)), controlled selectivity and direct magnetic separation (22.1 emicro g(-1)) in crude samples. After preconcentration and purification with magnetic MIPs nanoparticles, a sensitive chemiluminescence method was developed for determination of lysozyme in human serum samples. The results indicated that the spiked recoveries were changed from 92.5 to 113.7%, and the RSD was lower than 11.8%.
    Biosensors & Bioelectronics 10/2010; 26(2):301-6. · 6.45 Impact Factor
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    ABSTRACT: We developed in the present study a set of molecularly imprinted polymers (MIPs) by precipitation polymerization, using four members of tetracycline antibiotics (TCs) as templates (Oxytetracycline, Tetracycline, Chlortetracycline and Doxycycline). Then, based on the imprinting effect of different MIPs (TCs), Oxytetracycline and Chlortetracycline were chosen as mixed-templates to synthesize high selective MIPs for recognition of a family of analytes. And the characterization of obtained MIPs was analyzed by FESEM analysis, Brunauer-Emmett-Teller (BET) method, polymer size analysis, and determination of swelling ratio and COOH capacity. It was shown that the optimal imprinting factors of TCs on mixed-templates MIPs were more than 6.0 and the maximum binding amount of TCs were about 27 micromol g(-1) (Oxytetracycline), 35 micromol g(-1) (Tetracycline), 35 micromol g(-1) (Chlortetracycline) and 39 micromol g(-1) (Doxycycline), respectively. Finally, the mixed-templates MIPs were shown to be promising for on-line solid-phase extraction-HPLC-UV determination of trace TCs in foodstuffs. With a sample loading volume of 10 mL, the enhancement factors were in the range of 159-410.
    Biosensors & Bioelectronics 03/2010; 25(10):2218-24. · 6.45 Impact Factor
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    ABSTRACT: Abstract: The molecularly imprinted polymer (MIP) was prepared by precipitation polymerization using Sudan Red I as the template. To investigate the influence of porogenic solvent and the amount of template on recognition property, selective chromatographic evaluation and frontal chromatography were performed. The results indicated that the obtained MIP had the best affinity and selectivity to the template when the molar ratio of template to functional monomer was 1:8 and a mixture of 30 mL methanol and 10 mL acetonitrile was used as the porogenic solvent. The imprinted factor of optimal MIP for Sudan Red I was 2.32, and the total amount of the immobilized ligand was 0.50 micromol/g. This MIP displayed good specific recognition property for Sudan Red I and was used as the sorbent of solid phase extraction (SPE) to determine trace Sudan Red I in chili powders. The linear range was from 10 to 500 micromol/L with a correlation coefficient of 0.999. The detection limit was 3.3 micromol/L, the spiked recovery was between 95.87% and 98.41%, and the relative standard deviation (RSD) was lower than 3.1%. The developed method can be used for the routine detection of Sudan Red I in chili powders.
    Se pu = Chinese journal of chromatography / Zhongguo hua xue hui 11/2009; 27(6):764-8.