TOWARDS THE SYNTHESIS OF MOLECULARLY IMPRINTED POLYMERS BY MAGNETIC FIELD INDUCED POLYMERIZATION

The synthesis of molecularly imprinted polymers (MIPs) in the form of micro- or nanostructures, as well as their combination with other materials in composites, has been a major focus of research interest over the past decade. Thanks to their improved properties, these formats are especially suited for some applications, such as sensing, drug delivery or even analytical separations, over the more common bulky configurations. Different techniques have been applied to the preparation of nano and micro-MIP features including, electrical deposition, photolithography, microstereolithography, mechanical microspotting, soft-lithography, e-beam or electrospinning [1].

The incorporation of superparamagnetic iron oxide cores, quantum dots microcrystals or metallic nanoparticles, among others, has broadened up the applicability of MIPs to different fields [1]. In this context, the use of magnetic MIPs is particularly promising because the use of magnetic fields for the removal of the nanocomposites from the solutions is often much faster and efficient than centrifugation or filtration [2].

In this work, we describe the development of a novel approach to the preparation of molecularly imprinted polymer (MIP) coatings directly onto magnetic nanoparticles (MNPs) by using alternating magnetic fields (AMFs) to trigger the polymerization reaction. The MIPs were synthetized with rhodamine 123 (R123) as model template molecule, methacrylic acid (MAA) as functional monomer and trimethylolpropanetrimethacrylate (TRIM) as cross-linker. The amount of iron oxide nanoparticles (NPs, 10 mg) and the composition of the polymerization mixture were optimized to enable thermal polymerization of thin MIP shells onto the magnetic core by using electromagnetic heating, without altering the properties of the recognition layer. The thickness of the polymerized MIP layer grafted onto the MNPs was tuned by adjusting the dose of electromagnetic field (101.4 kHz, total power dissipation = 105 W). The resulting magnetic MIP nanoparticles (MNP-MIPs) have been characterized by ATR and X-ray diffraction (XRD) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The recognition properties of the imprinted polymer have been evaluated in batch rebinding experiments.

This work was supported by the Spanish Ministry of Economy and Competitiveness (grants CTQ2015-69278-C2 and MAT2015- 67557-C2-1-P), and the European Funds for Regional Development (FEDER).

[1] Bompart, M.; Haupt, K.; Ayela, C. A. Micro and Nanofabrication of Molecularly Imprinted Polymers. Top Curr Chem. 2012, 325, 83-110.

[2] Wackerlig, J.; Schirhagl, R.; Applications of Molecularly Imprinted Polymer Nanoparticles and Their Advances toward Industrial Use: A Review. Anal. Chem. 2016, 88, 250- 261.