Label-free electrochemical immunosensor based on antibody-immobilized Fe-Cu layered double hydroxide nanosheetas an electrochemical probe for the detection of ultra trace amount of prostate cancer biomarker (PSA)

Abstract

Here, a label-free immunosensor has been developed to detect prostate specific antigen as a diagnostic biomarker for prostate cancer. A pencil graphite electrode (PGE) coated with nanocomposites of iron-copper layered double hydroxide (Fe-Cu LDH) and reduced graphene oxide (rGO) was utilized as a sensor platform to capture the monoclonal anti-PSA antibody. The LDH/rGO nanocomposite can boost the electrical conductivity and enhance the surface area of the fabricated electrode; accordingly, it can efficiently amplify the electrode response and sensitivity in PSA detection. Electrochemical properties of the constructed sensor have been conducted utilizing cyclic voltammetry (CV), and electrochemical impedance spectroscopy(EIS). The PSA concentration level in serum samples was measured by monitoring the current changes of the Cu oxidation peak which was through the formation of antibody-PSA complexes on the surface of the electrode. The current response of the label-free immunosensor has been correlated to the concentration of PSA in a linear manner ranging from 100.0 fg/ml to 10.0 µg/ml with a limit of detection (LOD) of 63.24 fg/ml (S/N = 3). The morphology and structure of the synthesized Fe-Cu LDH/rGO nanocomposite was characterized using various analytical techniques such as field-emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD)and Fourier transform infrared (FTIR). The suggested immunosensor was employed to accurately and sensitively determine PSA concentration in serum samples with satisfactory results consistent with those achieved by enzyme-linked immunosorbent assay (ELISA) as a reference method. Finally, the obtained results indicate the promising application of the fabricated immunosensor in premature prostate cancer diagnostics.