Preparation of core-shell molecularly imprinted polymer via the combination of reversible addition-fragmentation chain transfer polymerization and click reaction
Analysis and Measure Center, Jilin Normal University, Siping 136000, China. Analytica chimica acta
(Impact Factor: 4.51).
11/2010; 680(1-2):65-71. DOI: 10.1016/j.aca.2010.09.017
In this paper, we demonstrated an efficient and robust route to the preparation of well-defined molecularly imprinted polymer based on reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. The alkyne terminated RAFT chain transfer agent was first synthesized, and then click reaction was used to graft RAFT agent onto the surface of silica particles which was modified by azide. Finally, imprinted thin film was prepared in the presence of 2,4-dichlorophenol as the template. The imprinted beads were demonstrated with a homogeneous polymer films (thickness of about 2.27 nm), and exhibited thermal stability under 255°C. The as-synthesized product showed obvious molecular imprinting effects towards the template, fast template rebinding kinetics and an appreciable selectivity over structurally related compounds.
Available from: Saliza Asman
- "Thus, it leads to homogeneous network polymer compared to FRP, which results in higher target affinity  and improves the binding properties of MIPs. Therefore, the RAFT polymerization has been widely used by several researches in various MIP polymerization methods, such as surface grafting  , suspension , precipitation   and core-shell polymerizations  . However, our previous work  demonstrated that the MIP obtained using RAFT polymerization in bulk polymerization method showed lower binding capacity and affinity compared to the ones obtained from the FRP bulk polymerization. "
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ABSTRACT: The adsorption behavior of molecularly imprinted polymers (MIPs) prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization process through the effect of polymer morphologies was described. In this study, two kinds of RAFT-MIPs were synthesized based on methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) and 2-hydroxyethyl methacrylate functionalized β-cyclodextrin (HEMA-β-CD) monomers, represented as RAFT-MMIP and RAFT-HMIP, respectively. The results of RAFT-MIPs were respectively compared with MMIP and HMIP prepared by free radical polymerization (FRP) process (without RAFT agent). The Field Emission Scanning Electron Microscope (FESEM) images showed that the RAFT-MMIP had slightly spherical and spongy-porous structure, and the MMIP had rough surface structure. Besides, the surface area of RAFT-MMIP was larger than MMIP. In contrast, the RAFT-HMIP formed non-porous particles with a smooth surface structure, while the HMIP formed a porous structure with a large surface area size. Through their physical characteristics, it proved that the morphological properties played an important factor which affected the adsorption behavior properties of MIPs, including kinetic, isotherm and thermodynamic studies. The superior physical characteristics of RAFT-MMIP demonstrated the greater equilibrium contact time, fast kinetic adsorption, higher adsorption rate, enhanced adsorption capacity and higher binding affinity. However, the non-porous RAFT-HMIP structure was poor in the adsorption behavior system. The RAFT polymerization successfully worked depending on the monomer used to generate potential MIPs.
Available from: Cinzia Passini
- "The presence of a reactive surface in the 'grafting from' approach allows a greater control of the polymerization process, above all in terms of length and density of surface polymer chains and for these reasons its use has been recently increased. On this basis, in order to efficiently develop thin controlled polymeric layers, in recent years, various surface molecular imprinting techniques based on 'iniferter' [Ruckert et al., 2002; Perez-Moral and Mayes, 2007; Barahona et al., 2010], 'reversible addition-fragmentation chain transfer' [Titirici and Sellergren, 2006; Pan et al., 2009; Chang et al., 2010] and 'atom transfer radical polymerization' [Wei et al., 2005; Zu et al., 2009; Sasaki et al., 2010] have been developed. Besides these methods to prepare controlled imprinted thin layers, a non-conventional approach to surface molecular imprinting has been reported [Matsui et al., 2002; Li et al., 2005]. "
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ABSTRACT: Molecularly imprinted polymers have been successfully used as selective stationary phases in capillary electrophoresis. Notwithstanding, this technique suffers from several drawbacks as the loss of molecular recognition properties in aqueous media and the lack of feasibility for imprinted systems directed towards highly polar templates soluble in aqueous environments only. Thus, the preparation of imprinted polymers for highly polar, water-soluble analytes, represents a challenge. In this work, we present an innovative approach to overcome these drawbacks. It is based on a surface molecular imprinting technique that uses preformed macromonomers as both functional recognition elements and cross-linking agents. A poly-2-hydroxyethyl-co-methacrylic acid linear polymer was grafted from the surface of silica capillaries. The grafted polymer was exhaustively esterified with methacrylic anhydride to obtain polyethylendimethacrylate-co-methacrylic acid linear chains. Then, as a proof of concept, an adequate amount of a very polar template like penicillin V was added in a hydro-organic mixture, and a thin layer of imprinted polymer was obtained by cross-linking the polymer linear chains. The binding behaviour of the imprinted and non-imprinted capillaries was evaluated in different separation conditions in order to assess the presence of template selectivity and molecular recognition effects. The experimental results clearly show that this innovative kind of imprinted material can be easily obtained in very polar polymerization environments and that it is characterized by enhanced molecular recognition properties in aqueous buffers and good selectivity towards the template and strictly related molecules.
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ABSTRACT: In this study, the magnetic yeast composites (mag–yeast) were successfully prepared by coating the chitosan layer containing γ-Fe2O3 nanoparticles onto the surface of the yeast. Then, the magnetic molecularly imprinted polymers (MMIPs) based on the mag–yeast were prepared by atom transfer radical polymerization (ATRP) which was occurred in mild reaction conditions. The MMIPs were characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and elemental analysis. The results demonstrated that spherical shaped MMIPs particles prepared via ATRP possessed magnetic property (Ms = 1.229 emu g−1) and magnetic stability (especially over the pH range of 5.0–11.0). The MMIPs were adopted as sorbents to selective recognition and separation of cefalexin (CFX). By the batch mode experiments, the results showed that adsorption behaviors of MMIPs were well described by the Freundlich isotherm and the pseudo-second-order kinetics. The MMIPs possessed excellent recognition capacity for CFX (36.86 mg g−1 at 298 K), and also exhibited outstanding selectivity for CFX over the other competitive compounds (such as sulfadiazine, tetracycline and ampicillin). Finally, the MMIPs were successfully applied to the selective solid phase extraction of CFX from the environmental samples.
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