Development of sensitive impedimetric immunosensor based on Pd-Au@carbon dots nanocomposite for prostate-specific antigen (PSA) detection

Cancer is a major public health problem and represents a significant burden of disease in the world. Among cancer concerning men worldwide, prostate cancer (PCa) makes its mark as one of the leading causes of cancer-related morbidity among men over 50 years of age [1]. In the last three decades, serum PSA has been shown to be the most reliable tumor marker for the early detection of PCa at the organ-confined stage and also monitoring the disease recurrence after treatment [2]. In this study, an impedimetric immunosensor based on screen-printed carbon electrode (SPCE) modified with Pd-Au@carbon dots for rapid and sensitive detection of prostate specific antigen (PSA) was developed. To achieve this goal, a zwitterionic polymer brush was fabricated on Pd-Au@carbon dots nanocomposite and then modification with boronic acid was conducted. To preserve the biological activity of antibody and improve the sensitivity, site-specific and self-oriented immobilization of antibodies via interaction of boronic acid and antibody were performed. The fabrication of immunosensor was characterized by using transmission electron microscopy, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The signaling mechanism of the proposed immunosensor was based on the increase in the [Fe(CN)6]3-/4- charge transfer resistance as an electrochemical probe in the presence of target analyte. The relationship of the impedance changes and the concentration of PSA was well fitted into a simple linear regression in the range of 0.6–280 pg mL−1. Limit of detection for the immunosensor was determined to be 0.6 pg mL−1. The developed immunosensor exhibits interesting characteristics such as wide linear range, low detection limit, and excellent specificity.