Construction and evaluation of AuNPs enhanced electrochemical immunosensors with [Fe(CN)6]3−/4− and PPy probe for highly sensitive detection of human chorionic gonadotropin

Human chorionic gonadotropin (HCG), a vital protein for pregnancy determination and a marker for trophoblastic diseases , finds application in monitoring early pregnancy and ectopic pregnancy . This study presents an innovative approach employing electrochemical immunosensors for enhanced HCG detection, utilizing Anti-HCG antibodies and gold nanoparticles (AuNPs) in the sensor platform. Two sensor configurations were optimized: BSA/Anti-HCG/c-AuNPs/MEL/e-AuNPs/SPCE with [Fe(CN) 6 ] 3−/4− as a redox probe (1) and BSA/Anti-HCG/PPy/e-AuNPs/SPCE using polypyrrole (PPy) as a redox probe (2). The first sensor offers linear correlation in the 0.10–500.00 pg∙mL −1 HCG range, with a limit of detection (LOD) of 0.06 pg∙mL −1 , sensitivity of 32.25 μA∙pg −1 ∙mL∙cm −2 , RSD <2.47 %, and a recovery rate of 101.03–104.81 %. The second sensor widens the HCG detection range (40.00 fg∙mL −1 -5.00 pg∙mL −1 ) with a LOD of 16.53 fg∙mL −1 , ensuring precision (RSD <1.04 %) and a recovery range of 94.61–106.07 % in serum samples. These electrochemical immunosensors have transformative potential in biomarker detection, offering enhanced sensitivity, selectivity , and stability for advanced healthcare diagnostics.