Supramolecular immobilization of redox enzymes on cyclodextrin-coated magnetic nanoparticles for biosensing applications

Mono-6-formyl-β-cyclodextrin moieties were attached to (3-aminopropyl)triethoxysilane-coated superparamagnetic Fe3O4 nanoparticles by reductive alkylation with NaBH3CN. The oligosaccharide-capped core–shell nanoparticles were employed as support for the supramolecular immobilization of two different adamantane-modified enzymes, tyrosinase and xanthine oxidase, through host–guest interactions. The enzyme-modified nanomaterial was further used to magnetically modify carbon paste electrodes for constructing amperometric biosensors toward cathecol and xanthine. The tyrosinase and xanthine oxidase based biosensors showed excellent electroanalytical behaviours, with linear ranges of 100 nM–12 μM cathecol and 5.0–120 μM xanthine, sensitivities of 12 mA/M and 130 mA/M, and low detection limits of 22 nM and 2.0 μM, respectively. The supramolecular nature of the immobilization approach was confirmed by electroanalytical methods.

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► Novel cyclodextrin-coated superparamagnetic Fe3O4 nanoparticles were prepared.
► They were used to immobilize adamantane-modified redox enzymes via host–guest association.
► Biosensors toward xanthine and cathecol were designed with these supramolecular nanocomplexes.