Molecularly Imprinted Nanoporous Polyacrylate Surface for Benzo(α)Pyrene Recognition

Molecularly imprinted polymers (MIPs) were synthesized using co-polymerization of methacrylic acid with cross-linking agent ethylene glycol dimethacrylate in the presence of benzo(α)pyrene (BAP) followed by the extraction of BAP from cross-linked polymer matrix. The MIP formed by this way contains nanopores, which are geometrically specific to the BAP molecule. BAP belongs to one of the carcinogenic airborne atmospheric pollutants. Morphological characteristics of MIP showed presence of nanopores with an average pore diameter of 27.19 Å and Brunauer-Emmett-Teller (BET) surface area of 827.87±1.63 m²g⁻¹. The adsorption capacity of BAP onto MIP was determined using equilibrium experiments. The cross-reactivity (CR) experiments were also conducted to found selectivity of BAP in the presence of 5 other polyaromatic hydrocarbon (PAH) compounds. The selectivity factors were calculated for MIP, based on experimental data derived from CR studies. It was found that the PAH molecules smaller being in molecular length (pyrene) than BAP, showed higher interference (up to 40%) compared with other PAH compounds. By increasing the concentration of other PAH compounds (100 μg mL⁻¹), the selectivity (α) of MIP was reduced from 3.5 to 1.6. The value of equilibrium binding constant for BAP, K _E=0.236 μg mL⁻¹, was larger than other PAH compounds (K _E values range from 0.011 to 0.028 μg mL⁻¹). These properties demonstrate that MIP prepared shows greater binding capacity and selectivity due to creation of homogenous nanopores patterned uniformly in the polymer matrix. This method of preparation of ordered materials at micro and nano-scale are useful in the field of nanodevices and sensors for environmental, defense and biomedical applications.