Electrocatalytic FeFe2O4 embedded, spermine-imprinted polypyrrole (Fe/MIPpy) nanozymes for cancer diagnosis and prognosis†

Developing synthetic materials, with enzyme-like molecular recognition capabilities, as functional receptors in electronic or electrochemical devices for the timely diagnosis of major diseases is a great challenge. Herein, we present the development of Fe/MIPpy nanozymes, characterized as enzyme-like artificial receptors, for the precise and non-invasive monitoring of cancer biomarkers in aqueous solutions and human saliva. Through the integration of PVA-stabilized FeFe₂O₄ nanocrystals in a molecularly imprinted conducting polypyrrole matrix, the Fe/MIPpy nanozymes demonstrate 424 nA cm⁻² nM⁻¹ sensitivity and 220 pM detection limit. Charge-transfer mechanisms, Fe/MIPpy–spermine interactions, and the principle of spermine recognition are investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The disposable Fe/MIPpy sensor operates wirelessly and offers rapid and remote quantification of spermine, making it a promising material for the development of cost-effective tools for non-invasive cancer diagnosis and prognosis.