Synthesis and characterization of a new magnetic restricted access molecularly imprinted polymer for biological sample preparation

Abstract

In this paper, a magnetic restricted access molecularly imprinted polymer (M-RAMIP) was proposed as a new sorbent for magnetic dispersive solid phase extraction of small molecules directly from untreated biological fluids. Fe3O4 nanoparticles were synthesized and functionalized with tetraethylorthosilicate and 3- (trimethoxysilyl) propyl methacrylate, resulting in Fe3O4@SiO2-MPS particles. A molecularly imprinted polymer selective to nicotine was synthesized on the Fe3O4@SiO2-MPS surface, resulting in a magnetic molecularly imprinted polymer (M-MIP). Finally, M-MIP particles were encapsulated with a bovine serum albumin (BSA) layer, resulting in the M-RAMIPs. A magnetic restricted access non-imprinted polymer (M-RANIP) was synthesized by the same procedure but in absence of the template molecule (nicotine). Adsorption kinetic and isotherm studies were best fitted to the fractional order and Sips models, respectively for kinetic and isotherm studies, attesting that the interactions occur by different mechanisms. The M-RAMIP presented higher adsorption capacities in comparison with M-RANIP. This is probably due to the presence of selective binding sites in the M-RAMIP. The selectivity test confirmed that the M-RAMIP was able to capture more nicotine than cotinine, caffeine, lidocaine, and cocaine in comparison with the M-RANIP, however, the covering with BSA reduced the selectivity in comparison with other MIPs from the literature. Protein exclusion capacities of about 79 % and 99 % were observed for M-MIP and M-RAMIP, respectively. M-RAMIP was used to extract nicotine from a human plasma sample, with precision and extraction recovery of about 16 and 27 %, respectively. Additionally, the same material was reusable in at least 50 extraction cycles with the same performance.