Facile synthesis of boronic acid-conjugated magnetic particles for an efficient extraction of dopamine neurotransmitter molecules

Abstract

Boronic acid-functionalized magnetic particles were synthesized in order to detect dopamine (DA) neurotransmitter molecules via fluorescent polydopamine formation. The sol-gel reaction of tetraethyl orthosilicate with magnetite clusters (Fe3O4) led to the formation of core-shell Fe3O4@SiO2, which then underwent surface functionalization with 3-aminopropyltrimethoxysilane (APTMS). The core-shell magnetic particles exhibited supermagnetic properties with a negligible remanence and coercivity. Finally. amine-terminated Fe3O4@SiO2 was conjugated with 4-formylphenylboronic acid (FPBA) using a sodium cyanoborohydride (NaBH3CN) as the reducing agent, and is called Fe3O4 @SiO2@FPBA. The composite particles could capture dopamine molecules via the formation of covalent cyclic ester bonds. The Fe3O4@SiO2@FPBA exhibited a high adsorption capacity (57 mu g of DA/g of composite particles), based on the fluorescent intensity of polydopamine converted from the oxidized DA under alkaline conditions. (C) 2018 The Japan Society of Applied Physics