Use of acrylic acid in the synthesis of molecularly imprinted polymers for the analysis of cyproheptadine

The synthesis and comparative characterization of molecularly imprinted polymers (MIPs) with cyproheptadine (CYP), using two different monomers, acrylic acid (AA) and methacrylic acid (MAA), are described.Polyacids (PA) [poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA)] were obtained by the radical polymerization of MAA and AA, respectively, in dichloromethane as the porogen solvent-imprinted medium. The non-covalent imprinting process was performed via thermal decomposition of an azo-initiator at 60 °C, using ethylene glycol dimethacrylate as the cross-linker and 2,2′-azobis(2-methylpropionitrile) as the initiator. The selectivities of MIPs and NIPs particles were evaluated in binding experiments of the four synthesized polymeric materials (MIPaa, MIPmaa, NIPmaa and NIPaa) with CYP. The effects of monomers on: a) the surface morphology, b) the binding capacity and c) the swelling properties of imprinted and non-imprinted polymers were studied and are presented here. Polymer material morphology was assessed with scanning electron microscopy (SEM). This revealed differences in monomer function, depending on which one was employed, as well as differences in function when polymerization occurred in the presence of template or without it. Non-specific retention of the template to NIPs was higher for NIPs-PAA polymers than for NIPs-PMAA materials. In terms of specific binding (ΔQ = QMIP − QNIP), MIPmaa showed the greatest value (53.47%) in comparison with MIPaa (50.07%).