Molecularly imprinted silica prepared with immiscible ionic liquid as solvent and porogen for selective recognition of testosterone

1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), an ionic liquid (IL) immiscible with water, was used as a new type of solvent and porogen for the preparation of molecularly imprinted silica. The new imprinted silica was prepared by a sacrificial spacer molecular imprinting approach with testosterone as template molecule. The new covalent monomer-template complex used in the imprinting procedure was synthesized via the reaction of 3-(triethoxysilyl)propyl isocyanate with testosterone. The imprinted silica was characterized by FT-IR spectroscopy, N2 gas adsorption–desorption isotherm and the high-resolution transmission electron microscopy. Moreover, the selective adsorption ability of the imprinted particles towards testosterone was investigated by the steady-state binding experiment with testosterone propionate as its structural analogue. Results showed that the imprinted silica obtained in this study had relatively homogenous structure with numerous mesopores, indicating that the IL used here is an excellent solvent and satisfactory porogen for the preparation of imprinted materials. Moreover, ILs are more environmentally friendly than traditional organic solvents due to their negligible vapor pressure. The imprinted silica possesses highly specific recognition property and high binding capacity towards testosterone, showing that the new imprinting technique is relatively successful.