Liquan Sun

Surface Molecular Imprinting on Manganese-Doped Zinc Sulfide Quantum Dots for Fluorescence Detection of Bisphenol A in Water

Manganese-doped zinc sulfide quantum dot based molecularly imprinted polymer composite nanoparticles were prepared. Bisphenol A served as the template and 3-aminopropyltriethoxysilane and tetraethoxysilicane were the functional monomer and cross-linker, respectively. The quantum dots exhibited excellent selectivity, fast adsorption kinetics, high stability, and good dispersion in aqueous media. The quenched fluorescence emission was proportional to the concentration of Bisphenol A without any preconcentration. This highly selective fluorescence sensor had a linear response from 10 to 700 nanograms per milliliter with a correlation coefficient of 0.9860. The relative standard deviation of five replicate measurements of 100 nanograms per milliliter Bisphenol A was 2.2 percent. The recovery of fortified Bisphenol A in water samples ranged from 98.70 to 105.50 percent.

Mn-doped ZnS QDs entrapped in molecularly imprinted membranes for detection of trace bisphenol A

This paper demonstrates a new strategy for producing fluorescent molecularly imprinted membranes (MIMs) for specific recognition of a target molecule. 3-Mercaptopropyltriethoxysilane-capped quantum dots (QDs) were first incorporated into hydrogel membranes of acrylamide and N,N′-methylenediacrylamide to fabricate QD-entrapped molecularly imprinted membranes. The fluorescence intensity of the QDs entrapped in the hydrogel membrane was quenched after being activated by the electron transfer between the QDs and bisphenol A. The quenched fluorescence emission intensity was proportional to the concentration of bisphenol A. Herein, trace levels of bisphenol A were rapidly detected through the quenching of the fluorescence intensity of the QD-entrapped membranes without any preconcentration processes. The linear detection ranges from 0.005 μM to 0.1 μM and with recoveries of 92–108% for bisphenol A. The QD-entrapped hydrogel membranes also showed quite good selectivity for the detection of bisphenol A.

Capillary column coated with geminal ionic liquids as stationary phases for gas chromatographic separation

Four geminal ionic liquids (GILs), namely, 1,4-bis(1,1′-butyl-3,3′- methylene- imidazolium)-benzene bis[(trifluoromethyl)sulfonyl]imide (BBMIB-NTf2), 1,4- bis(1,1′-butyl-3,3′-methylene-imidazolium)-benzene tetrafluoroborate (BBMIB-BF4), 1,4- bis(1,1′-butyl-3,3′-methylene-imidazolium)-benzene hexafluophosphate (BBMIB-PF6), and 1,4-bis(1,1′-methyl-3,3′-methylene-imidazolium)-benzene bis[(trifluoromethyl) sulfonyl] imide (BMMIB-NTf2), were synthesized. They were statically coated onto the inner walls of fused-silica capillary columns and used as stationary phases for gas chromatography. The evaluation of BBMIB-NTf2, BBMIB-BF4, BBMIB-PF6, and BMMIB-NTf2 as stationary phases is reported here for the first time. These new stationary phases exhibit efficiencies of at least 2.3 × 103 plates per meter. Abraham solvation parameter model was used to evaluate the solvation characteristics. The system constants indicated that the dipolarity/polarizability and the hydrogen-bond basicity play a major role among five mol...

Computational and experimental investigation of 4-nitrotoluene molecularly imprinted polymers

The density functional (DFT) method with the hybrid B3LYP exchange-correlation functional was proposed to study the intermolecular interactions between template and functional monomers at the prepolymerisation step. In the present work, 4-nitrotoluene (PNT) was chosen as the template. Six widely used functional monomers, methacrylic acid (MAA), acrylamide, 2-vinylpyridine, 4-vinylpyridine, methacrylamide and methyl methacrylate, were compared theoretically as the candidates for MIPs preparation. The computing result showing that MAA was a better functional monomer to prepare PNT molecularly imprinted polymers(MIPs). The attained complexes were optimised, and changes in the interaction energies, and atomic charges were used to predict the types of interactions existing in prepolymerisation complexes. Based on the conformational analysis and the calculated binding energies of PNT and MAA molecular systems, we have synthesize PNT molecularly imprinted polymers. The separation capability of this MIPs to PNT and its analog was evaluated when it worked as a HPLC column filling. The experimental results showed that the MIPs has an selective distinguish ability for PNT and its analog.

Tetracyclines Sorption in the Presence of Cadmium on River Sediments: the Effects of Sorption Mechanism and Complex Properties

Metal cations could enhance the sorption of tetracyclines but sometimes the effects are negligible. It is still not clear how these metals produce different effects. In this study, the sorption of chlortetracycline (CTC), tetracycline (TC), and oxytetracycline (OTC) was performed in the presence of Cd (II) to reveal the unknown mechanisms with two river sediments. It is found that Cd (II) could enhance the sorption of TCs on sediment SS, while it is negligible on sediment SY. For different tetracyclines, the enhancement effect by Cd (II) was more significant for CTC, while it is inferior for OTC and TC. Sorption isotherms of Cd (II) under strong and weak background electrolyte and pH decrease of sorption solutions indicate specific sorption is major on SY and cation exchange is significant on SS. Consequently, specific sorption is unfavorable for the enhanced sorption of TCs in the presence of Cd (II) because it is not favorable for the sorption of Cd-TCs by complexation and cation exchange. By the theoretical calculations, it is found that the significant enhancement of CTC is due to the higher electron affinity of Cd-CTC complex than the others to the surface groups. In conclusion, TCs sorption will not be affected by Cd (II) on sediments or soils with strong specific sorption characters of Cd (II).

Preparation and characterization of molecularly imprinted mesoporous organosilica for biphenol Z recognition and separation

Materials with large pore volume, fast binding kinetics and specific recognition are essential building blocks for sensors and assays. In this study, molecularly imprinted mesoporous organosilica (MIMO) was prepared by covalent surface imprinting methods with biphenol Z (BPZ) as template molecule and further characterized by FT-IR, TEM and N2 adsorption-desorption. Binding experiments results showed that MIMO has fast binding kinetics, good recognition for BPZ as compared to non-imprinted mesoporous organosilica (NIMO). Meanwhile, binding selectivity experiments demonstrated that MIMO had a high affinity to BPZ and BPA as compared to other structural analogues (BPS, catechol and resorcinol). Results demonstrate that MIMO has potential in sensor or separation application.

High porosity lysozyme imprinted polymers

High porosity lysozyme imprinted polyacrylamide polymers were synthesized by introducing nano-silica particles as pore-forming agent which could produce a lot of nano-pores after removing by HF etching. The adsorption capacity of the polymers with pore-forming agent (17.1mg/g) is much larger than those without adding silica (7.54 mg/g). The polymer in the form of “bulk” has pretty good mechanic strength which can overcome swelling and softness of reported crushed imprinted polymers and could be used in large-scale enrichment and separation of lysozyme from raw biological materials.