Abstract
The proportion of prostate-specific antigen (PSA) circulating in the free form can help to differentiate prostate cancer from benign prostate disease. In this paper, novel highly specific single-chain antibody (scAb) fragments were conjugated to magnetic particles (MPs) for the recognition and magnetic separation of free PSA (fPSA). A sandwich-type immunoassay method was developed, in which fPSA was captured by the scAb-conjugated MPs and labelled by a secondary antibody, conjugated to horseradish peroxidase (HRP) enzyme. The biosensor was constructed on carbon screen-printed electrodes (SPEs) modified with magnetic particles for increased surface area and fast reaction kinetics, thus enhancing binding capacity. The amperometric response was measured at −0.15 V, using hydrogen peroxide as the HRP substrate and hydroquinone (HQ) as the electrochemical mediator. The magneto-immunosensor demonstrated a sensitivity of 0.5 ng mL−1, with a linear detection range up to 10 ng mL−1 of fPSA.
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