Enzyme-free sandwich-type electrochemical immunosensor for highly sensitive prostate specific antigen based on conjugation of quantum dots and antibody on surface of modified glassy carbon electrode with core-shell magnetic metal-organic frameworks

The early diagnosis of cancer increases the chance of its treatment. In this study, an enzyme-free sandwich type of immunosensors is presented for prostate specific antigen (PSA), as prostate cancer biomarker. In this regard, the quantum dots (QDs) and magnetic metal-organic frameworks (MOFs) were used for labeling the secondary anybody and modifying the electrode surface, respectively. Herein, a bare glassy carbon electrodes is modified with iron magnetic nanoparticles with a core shell MOFs (magnetic framework Fe3O4@ TMU-10) and the primary antibodies (Ab(1)) are immobilized on the modified electrode. Moreover, the second antibody is successfully conjugated to a nickel-cadmium quantum dots as an electroactive non-enzymatic probe. The prepared immunosensor shows a linear range between 1 pg mL(-1)- 100 ng mL(-1) and the detection limit of 0.45 pg mL(-1) with acceptable selectivity, reproducibility and stability. The proposed sensor is also applied for determination of PSA in human serum samples and the results is confirmed by a reference method, which indicates its ability for clinical monitoring of the tumor marker.