A novel electroconductive interface based on Fe3O4 magnetic nanoparticle and cysteamine functionalized AuNPs: Preparation and application as signal amplification element to minoring of antigen-antibody immunocomplex and biosensing of prostate cancer

In this study, a novel electroconductive interface was prepared based on Fe3O4 magnetic nanoparticle and cysteamine functionalized gold nanoparticle. The engineered interface was used as signal amplification substrate in the electrochemical analysis of antibody-antigen binding. For this purpose, biotinilated-anti-prostate-specific antigen (PSA) antibody was bioconjugated with iron oxide magnetic nanoparticles (Fe3O4) and drop-casted on the surface of glassy carbon electrode (GCE). Also, secondary antibody (HRP-Ab2) encapsulated on gold nanoparticles caped by cysteamine was immobilized on the surface of GCE modified electrode. A transmission electron microscopy images shows that a sandwich immunoreaction was done and binding of Ab1 and Ab2 performed successfully. Various parameters of immunoassay, including the loading of magnetic nanoparticles, the amount of gold nanoparticle conjugate, and the immunoreaction time, were optimized. The detection limit of 0.001 mu g. L-1 of PSA was obtained under optimum experimental conditions. It is found that such magneto-bioassay could be readily used for simultaneous parallel detection of multiple proteins by using multiple inorganic metal nanoparticle tracers and are expected to open new opportunities for early stage diagnosis of cancer in near future.