Electrochemical immunosensor for prostate-specific antigens using a label-free second antibody based on silica nanoparticles and polymer brush

In this paper, we propose a sensitive electrochemical immunosensor synthesized using a surface-initiated atom transfer radical polymerization process for the detection of prostate-specific antigen (PSA). Electrochemical immunosensors based on polymer brush [oligo(ethylene glycol)methacrylate-co-glycidyl methacrylate] (OEGMA-co-GMA) were grown on plane Au and nanostructured (NS) Au electrodes, characterized and compared for their sensitivity to detect PSA. Due to a large capacity for antibody loading and high resistance to nonspecific antibody adsorption of POEGMA-co-GMA brush, the Au-NS immunosensor exhibited detection in a wide dynamic range of five orders of magnitude with an improved lower limit of detection of 2pgml−1, which was better than the synthesized immunosensor with the polymer brush grown on plane Au electrode. The Au-NS electrode showed improved detection sensitivity of 4.9μAng−1ml for PSA detection, which was almost 2 times better than the plane Au electrode. Finally, the use of silica nanoparticles (Si-NPs) conjugated with polyclonal antibody enhanced the response of the immunosensor. The proposed electrochemical immunosensor would be an exciting addition in medical diagnostics for the early detection of cancer biomarkers, e.g., PSA due to improved limit of detection (LOD); eventually helpful in circumventing cancer metastasis. [Display omitted] •Au-nanostructured electrode surface area was increased by 3.7 times.•The surface coverage by the polymer brush on it also improved by 7%.•Au-nanostructured electrode showed five orders of dynamic range for PSA detection.•The limit of detection was 2pgml−1, 2.1 times higher than the plane Au electrode.•Antibody-conjugated Si-NPs incorporated immunosensor further improved the sensing characteristics.