Aiqin Luo

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.

Synthesis and Adsorption Property of Hydrophilic Uridine Molecularly Imprinted Polymers

Hydrophilic uridine molecularly imprinted core-shell structured polymers (MIPs) were prepared via the distillation precipitation polymerization method using uridine, methyl methacrylate, ethylene glycol dimethacrylate, and 2, 2-azobisisobutyronitrile as the template molecule, functional monomer, cross-linker, and initiator, respectively. The adsorption kinetic behavior, equilibrium, and selectivity of uridine onto the MIPs were investigated by conducting a series of batch adsorption experiments. The results showed that the pseudo-first-order kinetic model provided a good correlation for the adsorption of uridine onto MIPs. The linear correlation coefficient R2 was 0.9884. The Langmuir and Freundlich modeling of the adsorption showed that the adsorption of the imprinted molecule uridine onto MIPs was fitted well to the Freundlich equation. The R2 value was 0.980. The separation capability of the MIPs to uridine and its analog was evaluated as HPLC column filling. The MIPs chromatographic column has a selectively distinguishing ability for uridine and its analog.

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.

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.

Imprinted Photonic Crystals for Levodropropizine Sensing

Levodropropizine (LDPZ) imprinted inverse opal films were prepared. Photonic polymers are able to transform the recognition of template to absorbance peak shift or reflection peak shift due to the feature size changes of the imprinted polymers. First, the compositions of the imprinted polymers were optimized to obtain both good selectivity and good swelling properties. Second, silica photonic crystals were prepared by colloidal self-assembly method. Silica photonic crystals with bright green color was infiltrated into the voids with LDPZ pre-polymerization solution and polymerized under heat. Molecularly imprinted inverse opal film (MIOF) and non-imprinted inverse opal film (NIOF) were obtained by etching with 1% HF acid. Finally, molecularly imprinted inverse opal film shows imprinting effect to LDPZ at pH 5.8 in 100mM PBS buffer.

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.