Molecularly imprinted core-shell hybrid microspheres for the selective extraction of vanillin
Molecularly imprinted polymers (MIPs) with a core-shell structure for efficient, reliable, and selective extraction of vanillin via solid-phase extraction (SPE) and incubation methods were developed using a sol–gel process based on (3-aminopropyl)triethoxysilane (APTES) as the functional monomer, tetraethoxysilane (TEOS) as the cross-linker, and vanillin as the template. The inorganic core composed of porous (SM1) and non-porous (SM2) silica microspheres was prepared by co-condensation of TEOS and (3-aminopropyl)trimethoxysilane) (APTMS) in a water-in-oil (W/O) macroemulsion. Thus synthesized materials were characterized in detail, and their molecular recognition properties and selectivity were demonstrated by evaluating adsorption capacity and binding kinetics at imprinted (MIP) and non-imprinted (NIP) control materials. The proposed binding mechanism takes advantage of the amino groups associated with APTES interacting with functional groups of the template molecules to form hydrogen-bonded complexes. Furthermore, synthesis conditions were optimized such that imprinting efficiency and adsorption capacity were maximized. Finally, it was demonstrated via incubation experiments that thus generated MIP core-shell hybrid microspheres provide rapid adsorption at high binding capacities (up to 5.64 mg g-1), excellent imprint factors (IF up to 2.37), and exceptional reusability (> 20 reused).