Ternary Hybrid γ-Fe2O3/CrVI/Amine Oxidase Nanostructure for Electrochemical Sensing: Application for Polyamine Detection in Tumor Tissue

Dichromate binds to surface-active maghemite nanoparticles (SAMNs) to form a stable core–shell nanostructures (SAMN@CrVI). The hybrid was characterized by Mössbauer spectroscopy, high-angle annular dark-field imaging, electron energy-loss spectroscopy, and electrochemical techniques, which revealed a strong interaction of dichromate with the nanoparticle surface. Electrochemical characterization showed lower charge-transfer resistance, better electrochemical performance, and more reversible electrochemical behavior with respect to naked SAMNs. Moreover, SAMN@CrVI is an excellent electrocatalyst for hydrogen peroxide reduction. Furthermore, an enzyme, namely, bovine serum amine oxidase (BSAO: EC 1.4.3.6), was immobilized on SAMN@CrVI by self-assembly to give a ternary hybrid nanostructured catalyst for polyamine oxidation (SAMN@CrVI-BSAO). SAMN@CrVI-BSAO was applied for the development of a reagentless, fast, inexpensive, and interference-free polyamine biosensor, which was successfully exploited for the discrimination of tumorous tissue from healthy tissue in human crude liver extracts.