Adsorption and specific recognition of DNA by using imprinted polymer layers grafted onto ionic liquid functionalized magnetic microspheres

Abstract

A molecularly imprinted polymer based on silica modified Fe3O4 microsphere and ionic liquid was prepared for the adsorption and specific recognition of DNA. Water-compatible imidazolium ionic liquids were introduced on the surface of silica-coated Fe3O4 microsphere, then used as the adsorbents, againsting DNA from salmon testes (stDNA) by combining immobilized template and surface imprinting techniques. The imprinted polymer layers were grafted onto ionic liquid functionalized microspheres through sol-gel approach using N-3-(3-triethoxysilylpropyl)-3-aminopropyl imidazolium chloride and N-3-(3-triethoxysilylpropyl)-3-mexyl imidazolium chloride as the functional monomers, and tetraethoxysilane as the cross-linker. Because both imidazolium ionic liquid and DNA are soluble in water, it is mandatory to implement an imprinted process in an aqueous medium to well maintain the integrity of the conformation. Fourier transform infrared spectrometry, thermogravimetric analysis, transmission electron microscopy, X-ray diffraction and vibrating sample magnetometry were employed to characterize the materials. The nanomaterials with multiple imprinting sites and biocompatible cavities exhibit high specific adsorption capacity of DNA (162 mg·g−1) and excellent rebinding selectivity (imprinting factor up to 6.6) against non-imprinted molecules at pH value of 5.10. Moreover, it is feasible to strip DNA from the highly cross-linked polymer network by using aqueous NaCl (1.0 M). The nanomaterials are cap able of capturing DNA from calf whole blood, which might provide a viable tool for DNA preconcentration, separation and recognition.