A label-free electrochemical immunosensor on gold-printed electrode for the electrochemical detection of C-reactive protein from blood samples
Nor Syafirah Zambry, Sushmeeka Nair Prathaban, Fatimah Ibrahim, Aung Thiha, Alexandria Sonia Karajacob, Nurul Fauzani Jamaluddin, Sharifah Faridah Syed Omar, Ina Ismiarti Shariffuddin, Aidawati Bustam, Sun Tee Tay
Abstract
The fabrication of a simple, label-free, electrochemical immunosensor for C-reactive protein (CRP) detection is presented using a custom-designed printed circuit board (PCB) gold electrode. To enhance the sensitivity of the sensing platform, the surface of the gold working electrode was modified with multi-walled carbon nanotubes (MWCNTs), leveraging its exceptional conductivity and biocompatibility. The label-free immunosensor operates on immunological principles, with anti-CRP antibodies covalently immobilized on the modified electrode to capture and quantify CRP levels, using differential pulse voltammetry (DPV). The immunosensor demonstrated high specificity to CRP, exhibiting a linear detection range of 1.25 to 80 μg/mL of CRP in 1 × PBS, and achieving a detection limit (LOD) of 0.745 µg/mL within 30 min. Notably, the immunosensor successfully detected CRP in human ethylenediaminetetraacetic acid (EDTA)-anticoagulated whole blood with a detection limit of 0.177 µg/mL, which is within the clinical range for sepsis (5 µg/mL). Furthermore, this immunosensor was able to detect CRP using only 2 µL of EDTA-anticoagulated whole blood samples. These findings highlight the potential of the CRP immunosensor platform for point-of-care (POC) testing in clinical settings, owing to its simple fabrication, ease of operation, low cost, and robust performance.