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Molecularly imprinted polymers (MIPs) are synthetic polymers with predetermined selectivity for a given analyte. One major problem associated with MIPs is the inaccessibility of a large fraction of the recognition sites that remain buried within the polymeric matrix. To address this problem, the high selectivity imparted by the imprinting technique and the porosity of three-dimensional (3D) graphene oxide (GO)-based porous materials were utilized in this work to prepare a 3D GO-based Cu(II)-ion-imprinted material (hereafter denoted as IIM) via one-pot reactions of GO, chitosan (CS), and glutaraldehyde in the presence of Cu(II). Results of equilibrium binding experiments show that IIM has a high template-ion binding capacity (1.75 mmol g -1 ) and good imprinting factor (2.19). Further, results of selectivity tests indicate that IIM has a high Cu(II)-recognition ability. IIM also has a fast binding rate and satisfactory reusability. In addition, the Langmuir isotherm model was well fitted with the experimental data, indicating the monolayer adsorption of Cu(II) ions. The present work provided a convenient approach to prepare 3D GO-based imprinted materials that are promising for enrichment or recycling of target compounds from wastewater.

A tryptophan (Trp) molecularly imprinted electrochemical sensor was fabricated by drop-coating an imprinted chitosan film on the surface of a glassy carbon electrode modified with multi-walled carbon nanotubes (MIP-MWCNTs/GCE). The surface morphology and electrochemical properties of the MIP-MWCNTs/GCE were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV), respectively. The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. The electrochemical performance of the MIP-MWCNTs/GCE with Trp showed that the signal of the oxidation current of Trp obtained with MIP-MWCNTs/GCE was significantly enhanced relative to that of the uncovered GCE, indicating that the modified electrode can accelerate electron transfer and has strong selectivity for Trp. The experimental conditions were optimized in parallel, and under the optimal conditions, the MIP-MWCNTs/GCE showed a good linear relationship between the Trp oxidation peak current and Trp concentrations in the ranges of 2.0 nM-0.2 μM, 0.2 μM-10 μM and 10 μM-100 μM The limit of detection (LOD) was 1.0 nM (S/N = 3), and the modified electrode had good reproducibility and stability. Finally, the MIP-MWCNTs/GCE was successfully applied to the determination of Trp in the human serum samples., (Copyright © 2019. Published by Elsevier B.V.)

In this paper, a tryptophan (Trp) molecularly imprinted chitosan film was prepared on the surface of an acetylene black paste electrode using chitosan as the functional polymer, Trp as the template molecule and sulfuric acid as the crosslinking agent. The surface morphologies of non-imprinted and imprinted electrodes were characterized by scanning electron microscopy (SEM). The formation of hydrogen bonds between the functional polymer and the template molecule was confirmed by infrared spectroscopy. Some factors affecting the performance of the imprinted electrode such as the concentration of chitosan, the mass ratio of chitosan to Trp, the dropping amount of the chitosan-Trp mixture, the solution pH, and the accumulation potential and time were discussed. The experimental results show that the imprinted electrode exhibit good affinity and selectivity for Trp. The dynamic linear ranges of 0.01-4 M, 4-20 M and 20-100 M were obtained by second derivative linear sweep voltammetry, and the detection limit was calculated to be 8.0 nM. The use of the imprinted electrode provides an effective method for eliminating the interference of potentially interfering substances. In addition, the sensor has high sensitivity, reproducibility and stability, and can be used for the determination of Trp in pharmaceutical preparations and human serum samples.

In order to improve the diffusion kinetics of molecularly imprinted materials (MIMs), applying imprinting technology to mesoporous materials is a promising strategy. In the present study, an imprinting approach based on the combination of mesoporous silica materials and molecular imprinting technology is reported. Molecularly imprinted material (MIM) for 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared by using 2,4-D as the template molecule, alkyne-modified β-cyclodextrin and propargyl amine as the combinatorial functional monomers and SBA-15 as the supporter. The functional monomers were anchored to the azide-modified SBA-15 by azide-alkyne Click reaction. The synthesized MIM was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermal gravimetric analysis (TGA), low-angle X-ray diffraction (XRD) and N 2 adsorption-desorption analysis. The interactions between template and functional monomers were studied by proton NMR analysis and UV-vis experiments. The results of the equilibrium binding experiments and selective tests showed that the prepared MIM has binding affinity and specificity for a group of analytes which have similar size and shape to those of template. Binding kinetic experiments demonstrated that the present imprinting approach can effectively enhance the mass transfer rate. The solid phase extraction of 2,4-D using MIM as the adsorbent was investigated. The extraction conditions for the processes of loading, washing and eluting were optimized. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for 2,4-D were 76.3-88.9% with relative standard deviations (RSD) of 3.48-7.64%., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Fluorescent molecularly imprinted polymers (MIPs) have attracted increasing attentions in recent years due to their high selectivity and sensitivity for target molecules. In this study, two cholic acid imprinted fluorescent polymers, i.e., MIP1 and MIP2, were prepared using 4-dimethylamino-N-allylnaphthalimide (F1) and 4-piperazinyl-N-allylnaphthalimide (F2) as the fluorescent functional monomers, respectively. The fluorescence intensity of MIP1 decreased linearly with the increase of the template concentration in the range of 1.50-120.0 μM, while the fluorescence intensity of MIP2 increased linearly with the increase of the template concentration in the range of 0.40-110.0 μM. The detection limits of MIP1 and MIP2 for cholic acid were 0.42 and 0.083 μM, respectively. The mechanisms of the fluorescence responsive of the imprinted polymers were discussed. The results of fluorescence measurement and binding experiments demonstrated that both imprinted polymers have high recognition abilities and binding affinities for the template. The imprinted polymers have been successfully applied to the determination of cholic acid in human serums. The present study indicated that 1,8-naphthalimide can be used as a modular building block for design and construction of various fluorogenic molecularly imprinted materials for practical sensing and separation., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this work, a new type of fluorescent probe for detection of doxorubicin has been constructed by the combined use of fluorescence resonance energy transfer (FRET) technology and molecular imprinting technique (MIT). Using doxorubicin as the template, the molecularly imprinted polymer thin layer was fabricated on the surfaces of carbon dot (CD) modified silica by sol-gel polymerization. The excitation energy of the fluorescent donor (CDs) could be transferred to the fluorescent acceptor (doxorubicin). The FRET based fluorescent probe demonstrated high sensitivity and selectivity for doxorubicin. The detection limit was 13.8 nM. The fluorescent probe was successfully applied for detecting doxorubicin in doxorubicin-spiked plasmas with a recovery of 96.8–103.8%, a relative standard deviation (RSD) of 1.3–2.8%. The strategy for construction of FRET-based molecularly imprinted materials developed in this work is very promising for analytical applications. [ABSTRACT FROM AUTHOR]

This paper reports a new strategy for preparation of 2D molecularly imprinted materials (MIM) through the exploitation of thiol-ene click chemistry. 2D MIM for cholesterol was prepared using cholesterol as the template, acrolyl-modified β-cyclodextrin (acrolyl-β-CD) as the functional monomer, and thiol-modified SBA-15 (thiol-SBA-15) as the supporter. In this method, acrolyl-β-CD molecules were assembled around the templates by formation of template-monomer inclusion compounds. Then the acrolyl-β-CD molecules were anchored to the walls of the mesopores of SBA-15 via the thiol-ene click chemistry. After removal of the template molecules, the resulting recognition sites were formed in the mesopores of SBA-15. TEM, XRD, and N adsorption-desorption analysis results demonstrated that the synthesized MIM had a highly ordered mesoporous structure. Results from FT-IR revealed that acrolyl-β-CDs have been successfully conjugated to SBA-15. The density of β-CDs attached on the MIM is determined by EA and TGA. The equilibrium binding amounts of MIM and non-imprinted materials (NIM) for cholesterol are 53.50 and 25.24 μmol/g, respectively. The 2D MIM exhibited binding affinity and specificity for a group of analytes which have similar size and shape to those of template. The application of the prepared materials as stationary phases in thin layer chromatography was investigated preliminarily. The imprinted materials had higher retention ability for the template than the NIM. The retention factors ( R) of cholesterol on MIM and NIM are 0.62 and 0.81, respectively. The solid phase extraction of cholesterol using MIM as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction column for cholesterol were 77.1-94.7 % with relative standard deviations (RSD) of 2.25-6.78 %. [ABSTRACT FROM AUTHOR]