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 (Ab1) 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.