Rong Cai

Magnetic dummy molecularly imprinted polymers based on multi-walled carbon nanotubes for rapid selective solid-phase extraction of 4-nonylphenol in aqueous samples.

In this paper, a highly selective sample clean-up procedure combining magnetic dummy molecular imprinting with solid-phase extraction was developed for rapid separation and determination of 4-nonylphenol (NP) in the environmental water samples. The magnetic dummy molecularly imprinted polymers (mag-DMIPs) based on multi-walled carbon nanotubes were successfully synthesized with a surface molecular imprinting technique using 4-tert-octylphenol as the dummy template and tetraethylorthosilicate as the cross-linker. The maximum adsorption capacity of the mag-DMIPs for NP was 52.4 mg g(-1) and it took about 20 min to achieve the adsorption equilibrium. The mag-DMIPs exhibited the specific selective adsorption toward NP. Coupled with high performance liquid chromatography analysis, the mag-DMIPs were used to extract solid-phase and detect NP in real water samples successfully with the recoveries of 88.6-98.1%.

An imprinted electrochemical sensor for bisphenol A determination based on electrodeposition of a graphene and Ag nanoparticle modified carbon electrode

In this study, a highly sensitive and selective imprinted electrochemical sensor based on a Ag nanoparticle and graphene modified carbon electrode with covalent anchoring and electrochemical reduction was prepared for the determination of bisphenol A (BPA) in aqueous solution. The imprinted film was fabricated by electrodepositing pyrrole in the presence of BPA onto the graphene and Ag nanoparticle modified electrode surface. The morphologies of the electrodes were characterized by scanning electron microscopy. The electrochemical performance of the imprinted electrochemical sensor was investigated by cyclic voltammetry and differential pulse voltammetry techniques in detail. The response currents of the imprinted electrochemical sensor exhibit a linear relationship toward the negative logarithm of the concentrations of BPA ranging from 1.0 × 10−11 to 1.0 × 10−8 mol L−1. The detection limit of the imprinted electrochemical sensor toward BPA is calculated to be 3.2 × 10−12 mol L−1 (S/N = 3). The imprinted electrochemical sensor was successfully applied to detect BPA in real plastic samples with good recoveries ranging from 93.3–103.0%.

Development and application of tetrabromobisphenol A imprinted electrochemical sensor based on graphene/carbon nanotubes three-dimensional nanocomposites modified carbon electrode

A novel imprinted electrochemical sensor based on graphene/carbon nanotubes three-dimensional (3D) nanocomposites modified carbon electrode was developed for the determination of tetrabromobisphenol A. The imprinted film was prepared by one-step electrodeposition technique with pyrrole as the functional monomer and tetrabromobisphenol A as the template molecule. The imprinted sensor was used for the determination of tetrabromobisphenol A with differential pulse voltammetry. A linear relationship between the response currents and the negative logarithm of tetrabromobisphenol A concentrations was obtained in the concentrations range of 1.0×10(-11)-1.0×10(-8) mol L(-1) with a detection limit of 3.7×10(-12) mol L(-1) (S/N=3). The proposed imprinted sensor showed excellent selectivity towards tetrabromobisphenol A. With good reproducibility and stability, the imprinted electrochemical sensor was used to detect tetrabromobisphenol A in fish samples successfully with the recoveries of 93.3-107.7%.

A sensitive and selective molecularly imprinted sensor combined with magnetic molecularly imprinted solid phase extraction for determination of dibutyl phthalate

A highly sensitive and selective molecularly imprinted (MIP) sensor combined with magnetic molecularly imprinted solid phase extraction (MMISPE) was developed for the determination of dibutyl phthalate (DBP) in complex matrixes. The magnetic molecularly imprinted polymer (MMIP) was synthesized as solid phase extraction (SPE) sorbet to extract DBP from complex matrixes and as sensing element to improve the selectivity of the imprinted sensor. The morphologies of MMIP and MIP-sensor were characterized by using scanning electron microscope (SEM) and transmission electron microscopy (TEM). The electrochemical performances of MIP-sensor were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The conditions of preconcentration, elution and electrochemical determination were studied in detail. Under the optimized experimental conditions, the response currents of the MIP-sensor exhibited a linear relationship towards DBP concentrations ranging from 1.0 × 10(-8)g/L to 1.0 × 10(-3)g/L. The limit of detection of the MMIP-sensor coupled with the MMISPE was calculated as 0.052 ng/L. The MMIP-sensor coupled with the MMISPE was applied to detect DBP in complex samples successfully.

Synthesis and properties of magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes for magnetic extraction of bisphenol A from water.

Novel magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes (MWNTs@MMIPs) with specific selectivity toward bisphenol A were synthesized using bisphenol A as the template molecule, methacrylic acid, and β-cyclodextrin as binary functional monomers and ethylene glycol dimethacrylate as the cross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared, vibrating sample magnetometer, and transmission electron microscopy. Batch mode adsorption experiment was carried out to investigate the specific adsorption equilibrium and kinetics of the MWNTs@MMIPs. The MWNTs@MMIPs exhibited good affinity with a maximum adsorption capacity of 49.26 μmol g(-1) and excellent selectivity toward bisphenol A. Combined with high-performance liquid chromatography analysis, the MWNTs@MMIPs were employed to extract bisphenol A in tap water, rain water, and lake water successfully with the recoveries of 89.8-95.4, 89.9-93.4, and 87.3-94.1%, respectively.

Molecularly imprinted electrochemical sensor based on amine group modified graphene covalently linked electrode for 4-nonylphenol detection.

In this work, an imprinted electrochemical sensor based on electrochemical reduced graphene covalently modified carbon electrode was developed for the determination of 4-nonylphenol (NP). An amine-terminated functional graphene oxide was covalently modified onto the electrode surface with diazonium salt reactions to improve the stability and reproducibility of the imprinted sensor. The electrochemical properties of each modified electrodes were investigated with differential pulse voltammetry (DPV). The electrochemical characteristic of the imprinted sensor was also investigated using electrochemical impedance spectroscopy (EIS) in detail. The response currents of the imprinted electrode exhibited a linear relationship toward 4-nonylphenol concentration ranging from 1.0 × 10(-11) to 1.0 × 10(-8) gm L(-1) with the detection limit of 3.5 × 10(-12) gm L(-1) (S/N=3). The fabricated electrochemical imprinted sensor was successfully applied to the detection of 4-nonylphenol in rain and lake water samples.

Fast separation and determination of erythromycin with magnetic imprinted solid extraction coupled with high performance liquid chromatography

In this paper a novel composite imprinted material based on poly(methyl methacrylate) (PMMA) coated magnetic multi-walled carbon nanotubes was successfully synthesized using erythromycin as the template and methacrylic acid as the functional monomer. The magnetic carbon nanotube molecularly imprinted polymers (mag-MWCNTs-MIPs) were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and vibrating sample magnetometery (VSM) in detail. The results showed that a magnetic imprinted layer was coated steadily on the surface of the multi-walled carbon nanotubes. Experiments of adsorption dynamics, static adsorption and selective recognition were conducted to evaluate the adsorption performance. The results showed that the mag-MWCNTs-MIPs displayed rapid dynamic adsorption toward erythromycin, which only needed 30 min to achieve adsorption equilibrium with a maximum adsorption capacity of 31.07 mg g−1. The mag-MWCNTs-MIPs were applied, coupled with high performance liquid chromatography (HPLC), to quickly enrich and detect erythromycin from fish tissue samples with recoveries of 82.7–88.5%. The mag-MWCNTs-MIPs can not only be collected and separated quickly and easily by an external magnet, but also have outstanding mechanical properties and specific recognition toward erythromycin.

Synthesis and Application of Novel Magnetic Lead (II) Ion Imprinted Polymers Based on Multiwalled Carbon Nanotubes

Novel magnetic ion imprinted polymers based on vinyl-functionlized multiwalled carbon nanotubes(MWNTs@MIIPs) with highly selective adsorption toward Pb2+ were synthesized using Pb2+ as the template,methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker.The MWNTs@MIIPs were characterized by scanning electron microscopy,Fourier-transform infrared analysis and vibrating sample magnetometer analysis.Adsorption studies demonstrated that the MWNTs@MIIPs possessed excellent adsorption and selective recognition ability towards Pb2+ with a maximum capacity of 25.9 mg/g.And the selectivity factor of MWNTs@MIIPs towards Pb2+/Cu2+,Pb2+/Zn2+ Pb2+/Co2+,Pb2+/Mg2+,Pb2+/Cd2+and Pb2+/Ni2+ was 2.3,2.5,2.1,2.2,2.1 and 2.4,respectively.Combined with atomic absorption spectrometric analysis technology,the MWNTs@MIIPs were successfully applied for separation and enrichment trace Pb2+ in environmental real samples with the enrichment factor of 40.5.