Electrochemical Immunosensor for C-Reactive Protein Detection Using an Optimized Bioinspired Ni-Doped Copper Ferrite Nanocomposite Interface for Cardiovascular Disease Management

Currently, cardiovascular diseases (CVDs) are the leading cause of death globally. According to the WHO, the number of CVDs-related deaths increases by 20% annually. C-reactive protein (CRP), a biomarker for CVDs that sharply rises during cardiac events, was used to monitor these critical conditions at an early stage. To address the need for highly sensitive, selective, and portable CRP detection, a nickel-doped copper ferrite nanoparticle-based electrochemical biosensor was developed. In this work, optimized nickel-doped copper ferrite (Ni_(0.10)CuFe₂O₄) nanoparticles (NPs) were synthesized by doping copper ferrite NPs with varying nickel concentrations (0.05, 0.10, 0.15, and 0.20 M) via a hydrothermal method using aqueous leaf extract of <i>Magnolia grandiflora</i>. The NPs were characterized by using XRD, FT-IR, UV, SEM, EDX, and HR-TEM/TEM. The synthesized NPs were deposited on a functionalized indium tin oxide (ITO) surface via the electrophoretic deposition (EPD) method. Electrochemical sensing was performed by using electrochemical impedance spectroscopy (EIS). The biosensor demonstrated linear detection of CRP biomarkers across a range of 0.5 to 500 ng/mL, with a sensitivity of 5.426 Ω/ng cm² at 0.5 ng/mL and 0.68244 Ω/ng cm² at 500 ng/mL. The limit of detection (LOD) values were 0.038 ng/mL (lower concentration range) and 0.033 ng/mL (higher concentration of the analyte range).