A novel PPtNPs/rGO@Cu(BDC-NH₂) MOF/PEDOT@PB/SPCE platform for ultra-sensitive label-free electrochemical immunosensor...

A novel label-free electrochemical immunosensor was constructed to quantify prostate-specific antigen (PSA) in human serum. A poly(3,4-ethylenedioxythiophene) and Prussian blue nanocomposite (PEDOT@PB) was used to a screen-printed carbon electrode (SPCE) modification to construct the platform followed by a nanocomposite of reduced graphene oxide and copper metal-organic framework (rGO@Cu(BDC-NH₂) MOF), that was then decorated with porous platinum nanoparticles (PPtNPs). In this system, PEDOT@PB served as a redox probe. The rGO@Cu(BDC-NH₂) MOF offered a high surface area and exceptional electroconductivity to facilitate PPtNPs chemisorption through coordination with the amino groups of Cu(BDC-NH₂) MOF. The PPtNPs provided high conductivity and a high surface area to enhance the immobilization of PSA antibody (Ab_PSA), thereby improving sensor performance. PSA was quantified using differential pulse voltammetry (DPV) by monitoring the decrease in the oxidation peak current of the PB probe as the antigen-antibody immunocomplex forms to create an insulating layer that hinders electron transfer. The proposed sensor demonstrated excellent performances under optimized conditions, with a linear range of 1.0 × 10^-7 to 10^-1 ng mL^-1 and a low limit of detection of 7.8 × 10^-8 ng mL^-1. The sensor also demonstrated excellent stability, enhanced sensitivity, and acceptable selectivity. There was no meaningful statistical difference between the results obtained from the sensor and those from the electrochemiluminescence immunoassay (P > 0.05).