Development of Co₃[Co(CN)₆]₂/Fe₃O₄ Bifunctional Nanocomposite for Clinical Sensor Applications

In this study, a magnetically separable three-dimensional (3D) Co3[Co(CN)6]2/Fe3O4 nanocomposite comprising magnetic nanoparticles (NPs) adsorbed on the nanocubes of a cobalt Prussian blue analogue was prepared. The nanocomposite exhibited enhanced electrochemical performance in Co2+/Co3+ conversion, while the superparamagnetic behavior of the magnetite NPs was preserved even after adsorption on the nanocubes. Increased Faradaic currents were observed in the cyclic voltammograms (CV) for Co3[Co(CN)6]2/Fe3O4 in comparison with the CV of isolated Co3[Co(CN)6]2. This increase was attributed to supramolecular charge transfer between the cobalt Prussian blue analogue and the magnetic NPs and the larger amount of electroactive species on the electrode. Transmission electron microscopy images showed well-defined Co3[Co(CN)6]2 nanocubes that had edge lengths of 21–140 nm and were decorated with spherical magnetite NPs less than 10 nm in diameter. Interestingly, an intimate contact between the nanocubes and aggregate formation was avoided by Fe3O4 NPs. The composition, morphology, and surface properties of the nanohybrid material were assessed by UV–vis absorption spectroscopy, FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, and Brunauer–Emmett–Teller surface area. The analytical results of nanocomposite showed main bands, crystalline phases, and structures associated with Fe3O4 and Co3[Co(CN)6]2. The bifunctional properties of Co3[Co(CN)6]2/Fe3O4 are potentially useful for building novel (bio)sensors and magnetic devices for clinical applications.