Fabrication of an immunosensor for early and ultrasensitive determination of human tissue plasminogen activator (tPA) in myocardial infraction and breast cancer patients

Haidar Saify Nabiabad, Khosro Piri, Fatemeh Kafrashi, Abbas Afkhami, Tayyebeh Madrakian

Sensitive detection of biomarkers will mean accurate and early diagnosis of diseases. A tissue plasminogen activator (tPA) has a crucial role in many cardiovascular diseases and it is related to many processes such as angiogenesis in cancer cells. Therefore, sensitive determination of tPA is important in diagnosis and clinical research. tPA monoclonal antibody was covalently attached onto single-wall carbon nanotubes (SWCNTs) using diimide-activated imidation coupling. Functionalized SWCNTs were immobilized onto a glassy carbon electrode and the modification process was investigated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), SEM, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Cyclic voltammograms (CVs) in a scan rate of 100 mVs-1 was studied and comparisons were made between the modified glassy carbon electrodes (immobilized with antibodies) as a working electrode before and after the formation of tPA-antibody complex. Results of the SDS-PAGE demonstrated that the antibody was covalently and site directly attached to the SWCNTs. The fabricated biosensor provided a good linear response range from 0.1 to 1.0 ng mL-1 with a low detection limit of 0.026 ng mL-1. The immunosensor showed selectivity, reproducibility, good sensitivity, and acceptable stability. Satisfactory results were observed for early and sensitive determination of tPA in human serum samples. For the first time, such specific biosensor is currently being fabricated for tPA in our laboratories and successfully could determine tPA in myocardial infraction and breast cancer patients. Graphical abstract Fabricated biosensor for determination of tPA.