Selective Separation of Thyroid-Hormone-Receptor-Binding Substances Using Molecularly Imprinted Polymers

To date, an identification protocol for endocrine disruptors that bind to the thyroid hormone receptor (TR) has not been established. A method for screening and identifying TR-binding substances is highly required due to the existence of unknown TR-binding substances from the environment. Here, we conceived a chromatographic method using a molecularly imprinted polymer (MIP) to create a novel screening protocol for the endocrine disruptors. A receptor-imitating MIP was prepared using N-acetylthyroxine (AcetylT4) and 4-vinylpyridine as a pseudo-template and a functional monomer, respectively, based on the existing molecular recognition mechanism of the TR. The receptor-imitating MIP provided molecular recognition ability for all the TR-binding substances that were employed in this study. The prepared MIPs were packed into a high-performance liquid chromatography column for the simultaneous analysis of TR-binding and non-binding substances. The former was strongly retained, while the latter was not. The presence or absence of TR-binding/non-binding activity resulted in successful dichotomous separation. Additionally, the surface imprinting technique was applied to improve the separation performance of the MIP packing material. MIP-coated uniformly sized silica-based particles of 5 μm were successfully prepared, and the MIP-coated silica column enabled more efficient dichotomous separation of TR-binding and non-binding substances.