Collagen-Coated Superparamagnetic Iron Oxide Nanoparticles as a Sustainable Catalyst for Spirooxindole Synthesis

In this work, a novel magnetic organic-inorganic hybrid catalyst was fabricated by encapsulating magnetite@silica (Fe3O4@SiO2) nanoparticles with Isinglass protein collagen (IGPC) using epichlorohydrin (ECH) as crosslinking agent. Characterization studies of the prepared particles were accomplished by various analytical techniques specifically, Fourier transform infrared (FTIR) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and Brunauer−Emmett−Teller (BET) analysis. The XRD results showed a crystalline and amorphous phase which contribute to magnetite and isinglass respectively. Moreover, the formation of the core/shell structure had been confirmed by TEM images. The synthesized Fe3O4@SiO2/ECH/IG was applied as bifunctional heterogeneous catalyst in the synthesis of spirooxindole derivatives demonstrating excellent catalytic properties, stability and recyclability.