An ultrasensitive sandwich-type electrochemical immunosensor for PSA detection: employing layer-by-layer self-assembly with poly(thionine)/carbon nanotube multilayers as electron mediators and hemin-functionalized PEI/SiO 2 nanoparticles as signal amplifiers

This study presents an ultrasensitive sandwich-type electrochemical immunosensor for prostate-specific antigen detection, employing hemin-functionalized polyethyleneimine/silica nanoparticles (hemin/PEI/SiO 2 NPs) as high-efficiency catalytic labels.