An Fe3O4/PEDOT:PSS nanocomposite as an advanced electroconductive material for the biosensing of the prostate-specific antigen in unprocessed human plasma samples

A novel sandwich-type biosensor based on a signal amplification strategy of various nanocomposites was developed to monitor the prostate-specific antigen (PSA) in real samples. The engineered immunosensor was fabricated using iron oxide magnetic nanoparticles modified with a polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) [Fe3O4/PEDOT:PSS] conductive nanocomposite that utilized the immobilization of primary antibodies (biotinylated antibody (Ab1)). In order to improve the electron transfer rate, a cysteamine-capped gold nanoparticle (AuNPs-CysA) was applied for conjugation with a secondary antibody (HRP-Ab2). The fabrication procedure was investigated by square wave voltammetry. Under optimized experimental conditions, the calibration curve showed a wide linear range (0.001-0.5 mu g L-1) for the PSA biomarker with a low limit of quantification of 0.001 mu g L-1. Finally, satisfactory results were obtained for the determination of PSA in untreated human plasma samples, indicating the potential of the immunoassay for applications in clinical bioanalysis.