Preparation of core-shell molecularly imprinted polymer via the combination of reversible addition-fragmentation chain transfer polymerization and click reaction

ArticleinAnalytica chimica acta 680(1-2):65-71 · November 2010with5 Reads
DOI: 10.1016/j.aca.2010.09.017 · Source: PubMed
Abstract
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.
    • "RAFT has been largely applied to the surface grafting of imprinted polymers [94][95][96][97][134][135][136][137][138][139]and a series of different approaches has been reported based on the surface functionalization with the different species involved in the polymerization process, i.e. with a radical initiator [140], a RAFT agent [141][142][143][144]or a vinyl group [145]. Which approach to choose depends on the specific reagents and on their chemistry, but most of the published work deals with the grafting of the RAFT agent. "
    [Show abstract] [Hide abstract] ABSTRACT: Since the pioneering work of Wulff and Mosbach more than 30 years ago, molecular imprinting of synthetic polymers has emerged as a robust and convenient way for synthesizing polymeric receptor materials bearing specific recognition sites for target molecules. The resulting materials, molecularly imprinted polymers (MIPs), are therefore commonly referred to as ‘plastic antibodies’. They are obtained by polymerizing a scaffold around a target, or a derivate thereof, which acts as a molecular template. MIPs have been successfully applied in many areas including affinity separation, immunoassays, chemical sensing, solid-phase extraction, drug delivery, cell and tissue imaging, direct synthesis and catalysis. In terms of affinity and selectivity, MIPs are on a par with biological receptors like antibodies, and this is accompanied by a superior chemical and physical stability, compatibility with organic media, reusability, easy engineering and low cost. These advantages represent the main reasons for the wide interest raised around molecularly imprinted materials. Mainly produced by free radical polymerization (FRP) of vinyl monomers, MIPs have also taken advantage of the introduction of controlled/living radical polymerization (CRP) techniques, which have literally transformed polymer chemistry over the last decade. This review describes the advantages arising from the use of CRP in synthesizing MIPs, both in terms of sheer binding properties as well as for their remarkable potential for post-polymerization functionalization, for the synthesis of MIP nanomaterials and for the integration of MIPs into composites and hybrid materials. The benefits of using CRP are critically assessed with respect to the still largely applied FRP and guidelines are provided for choosing the most convenient technique to fit a specific targeted application of MIPs.
    Article · May 2016 · Journal of Molecular Recognition
    • "Thus, it leads to homogeneous network polymer compared to FRP, which results in higher target affinity [14] 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 [15] [16], suspension [17], precipitation [8] [18] and core-shell polymerizations [13] [19]. However, our previous work [20] 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. "
    [Show abstract] [Hide abstract] 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.
    Full-text · Article · Feb 2016
    • "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]. "
    [Show abstract] [Hide abstract] 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.
    Full-text · Article · Jun 2012
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