Nanostructured Bismuth-Doped Cobalt Ferrite (Bi_<i>x</i>CoFe₂O₄) Interfaces for the Impedimetric Detection of C-Reactive Protein in Cardiovascular Disease Monitoring

Globally, cardiovascular disease (CVD) constitute a primary source of morbidity and mortality. Timely and precise diagnosis of pertinent biomarkers and function parameters can provide valuable insight into the physiological and pathological processes associated with CVD. This research aims to develop a new sensing platform for C-reactive protein (CRP) to detect cardiovascular disease, utilizing an indium tin oxide (ITO) electrode modified with hydrothermally synthesized bismuth-doped cobalt ferrite (Bi_<i>x</i>CoFe₂O₄) nanoparticles (NPs) by varying bismuth concentrations of (<i>x</i> = 0.5, 0.10, 0.15, 0.20 M). These synthesized doped NPs are characterized by using XRD, FTIR, UV, scanning electron microscopy (SEM), HR-TEM, energy-dispersive X-ray (EDX), dynamic light scattering (DLS), and AFM techniques to ascertain their morphological and structural properties. The modified material was deposited on the ITO electrode via the electrophoretic deposition (EPD) method. The electrochemical study indicates that the modified electrode exhibits a higher current density than the bare ITO electrode. CRP immobilization was performed by the drop casting method, and the electrochemical impedance spectroscopy (EIS) demonstrates that the developed immunoelectrode exhibits a linear concentration at a lower range from 0.5 to 100 ng/mL and a higher range of 100-500 ng/mL. The sensitivity has been observed at 0.376305 and 0.05492 Ω/ng cm², with the limit of detection (LOD) of 0.15 and 0.22 ng/mL, the limit of quantification (LOQ) of 0.51 and 0.74 ng/mL, and the response time of 20 s. The study is significant in the field of CVD, as it assesses inflammation and cardiovascular risk.