Fabrication of alkoxysilane substituted polymer-modified disposable biosensing platform: Towards sperm protein 17 sensing as a new cancer biomarker

SP17 is a mammalian protein found in the testis and spermatozoa that have been identified as a tumor-associated antigen in a range of human cancers. A unique method for fabricating the first ultrasensitive, selective, and label-free immunosensor for the detection of SP17, a new cancer biomarker in complicated serum samples, is presented in this paper. This immunosensor was also the first biosensor built using a disposable ITO sheet modified with an aminosilane known as APTMS as an immobilization platform for fabricating the SP17 biosensor. The immobilization of chemical and biological species onto the electrode surface was cross-verified by various analytical and morphological techniques. Stepwise modifications done on the immunoelectrodes were also studied using electrochemical techniques. Selective interaction between anti-SP17 and SP17 with varying concentrations (100-5000 pg mL^-1) was measured with the DPV technique. The immunosensor exhibited low LOD and LOQ of 70.07 and 233.57 pg mL^-1, respectively, with a sensitivity of 0.013 μA mL pg^-1 cm^-2. The fabricated immunosensor performance was analyzed by quantifying the SP17 concentrations in patient serum samples. The data obtained from the developed immunosensor demonstrated excellent reproducibility, repeatability, and selectivity among various interferants, including cancer biomarkers. Further, the observed results have been validated via ELISA, which showed good agreement with the electrochemical results. This could establish a new platform for detecting other cancer biomarkers and can be employed for clinical diagnostics applications.