Electrochemical biosensing of alpha-fetoprotein based on carboxylated multi-walled nanotube-polyAzur A (in DES)-gold nanoparticles.

AFP, a cancer biomarker, is monitored during fetal development and in the serum of pregnant women. Sensitive and rapid monitoring of AFP is crucial for effective management. In this study, screen-printed carbon electrodes (SPCEs) modified with multi-walled carbon nanotubes (MWCNT-COOH), polyAzur A (PAA), which was prepared in a deep eutectic solution (DES), and gold nanoparticles (AuNP) were fabricated. AFP biosensors were developed for practical, sensitive, low-cost, and rapid detection of AFP. Optimizations of nanostructures (MWCNT-COOH, AuNP) and polymers (PAADES) were performed. The MWCNT-COOH, PAADES, and AuNP-modified SPCEs were characterized by FE-SEM-EDX, FTIR, and XRD techniques. The amounts of 6-MOH, APTES, GA, and anti-AFP used to prepare AFP biosensors and the times for anti-AFP and AFP were also optimized. The linear range and detection limit of the AFP biosensors were established as 0.5-250 ng/mL and 0.15 ng/mL, respectively. Stability and shelf life were monitored for 60 days and 24 weeks, respectively. The AFP biosensors exhibited high selectivity (97.5%) for AFP in the presence of other cancer biomarkers, including cancer antigen 125 and human epididymis protein 4. Reproducibility tests of the AFP biosensors demonstrated responsiveness across five replicates (RSD: 4.80%, n = 5). Although designed to be disposable, the developed AFP biosensors were reusable up to two times. AFP levels in commercially obtained blood serum were measured by DPV for 2 minutes using AFP biosensors. The developed AFP biosensors are potential candidates for use in point-of-care testing.