Ultrasensitive electrochemical immunosensor for the detection of C-reactive protein antigen†

Cardiovascular disease is one of the leading causes of premature death worldwide, and the determination of C-reactive protein (CRP) from human serum is of vital importance for the diagnosis of the disease. For this study, we have developed an electrochemical immunosensor based on onion-like carbon@polyacrylonitrile (OLC-PAN) for the detection of CRP antigens. This was accomplished by immobilizing CRP antibodies on a modified glassy carbon electrode (GCE). Several electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were employed to evaluate the electrochemical detection of the CRP antigen. This ultrasensitive method for CRP antigen detection exhibited a very good logarithmic plot from −4.52 to −12.05 g mL⁻¹ and a limit of detection (LOD) of 0.9 fg mL⁻¹. The high selectivity, sensitivity, and stability of the developed electrochemical immunosensor would facilitate miniaturization for point-of-care applications and the efficient diagnosis of cardiovascular diseases.