Highly sensitive and selective detection of KLK4 in human serum with a low-cost electrochemical biosensor

An ultrasensitive impedimetric immunosensor was fabricated using a poly(glycidyl methacrylate) (PGMA) polymer-covered indium tin oxide (ITO) platform for the quantification of kallikrein 4 (KLK4), an important prostate cancer biomarker. PGMA had suitable biocompatibility and nontoxicity for loading of antiKLK4 antibodies on the ITO substrate surface. Anti-KLK4 biomolecules were directly attached to the PGMA-covered electrode surface via epoxy groups of the PGMA polymer. The preparation method for the PGMA matrix-modified electrode was simple and inexpensive. The proposed biosensor immobilization layers coated on the ITO electrode were characterized with electrochemical techniques. The experimental parameters that affect biosensor response were optimized, and the suggested sensor showed a linear response from 0.04 pg/mL to 8 pg/mL with a low detection limit (LOD) of 12.21 fg/mL. Moreover, it had acceptable stability, reproducibility, and repeatability. Additionally, the disposable biosensor offered excellent reliability and accuracy in KLK4 analysis, suggesting that it could be used as an alternative technique in clinical diagnosis.