Selective fluorescence detection of proteins using molecularly imprinted hydrogels with aggregation-induced emission

Molecular imprinting is known as a method for synthesizing materials that selectively adsorb specific molecules. The polymers obtained by this method are inexpensive, highly chemically stable, and easy to prepare, but there is a problem that definite and easy detection of the adsorption of target molecules is difficult. We aimed to achieve selective fluorescence detection of proteins by introducing fluorescent molecules into a molecularly imprinted hydrogel (MIH). For fluorescence detection, we used aggregation-induced emission (AIE), which has been attracting attention in recent years. Molecules exhibiting AIE have the characteristic that their fluorescence intensity increases due to factors such as aggregation of molecules or chemical interaction with target molecules. A new AIE monomer was synthesized, and its characteristics were evaluated. The MIHs were prepared with an AIE monomer, functional monomers, poly(ethylene glycol)diacrylate as a crosslinker, and lysozyme as a target protein. The MIHs showed selective adsorption for lysozyme and a specific increase in fluorescent intensity. Even in a protein mixture sample, we achieved optical detection for lysozyme.