Screen‐Printed Electrochemical Immunosensor Modified with Gold Nanoparticles for the Detection of Prostate Cancer Biomarker Human Kallikrein 2

Initially, a printed electrode was fabricated on a polyethylene terephthalate (PET) substrate using an ink based on graphite, carbon black, and nail polish. The working electrode was then modified with gold nanoparticles, followed by the sequential immobilization of antibodies specific to KLK2, bovine serum albumin (BSA), and KLK2 antigen as the target molecule. Several parameters were optimized to achieve the best performance of the immunosensor: antibody incubation time (40 min), BSA incubation time and concentration (30 min, 1.50 mg mL −1 ), antigen incubation time (60 min), supporting electrolyte pH (7.50), and supporting electrolyte concentration (0.01 mol L −1 ). After each modification step, the sensor was thoroughly washed with a 0.10 mol L −1 phosphate buffer (pH 7.00) and dried using a nitrogen stream. Reproducibility and interference studies demonstrated that the sensor exhibited good reproducibility and specificity for KLK2 detection. Subsequently, the sensor was applied to determine KLK2 in synthetic serum samples, achieving excellent recovery values ranging from 95.6% to 102%. These results suggest that the screen‐printed electrode (SPE)/AuNP/anti‐KLK2/BSA sensor holds promise for analyzing KLK2 in real serum samples.