Enhanced Visual Wireless Electrochemiluminescence Immunosensing of Prostate-Specific Antigen Based on the Luminol Loaded into MIL-53(Fe)-NH₂ Accelerator and Hydrogen Evolution Reaction Mediation

Abstract

A sensitive prostate-specific antigen (PSA) detection method using a visual-readout closed bipolar electrode (BPE) system has been introduced by integration of hydrogen evolution reaction (HER) in cathodic pole and electrochemiluminescence (ECL) of luminol loaded within the MIL-53(Fe)-NH₂ (L@MIL-53(Fe)-NH₂) in the anodic pole. The cathode of the BPE was electrochemically synthesized by 3D porous copper foam, followed by decorating with nitrogen-doped graphene nanosheet and ruthenium nanoparticles. As an alternative, we employed carboxylate-modified magnetic nanoparticles (MNPs) for immobilization of the primary antibody (Ab1) and utilized the L@MIL-53(Fe)-NH₂ conjugated to secondary antibody (Ab2) as a signaling probe and coreaction accelerator. After sandwiching the target PSA between Ab1 and Ab2, the MNP/Ab1-PSA-Ab2/L@MIL-53(Fe) were introduced to a gold anodic BPE. Finally, the resulting ECL of luminol and H₂O₂ at the anodic poles was monitored using a photomultiplier tube (PMT) or digital camera. The PMT and visual (camera)-based detections showed linear responses from 1 pg mL^-1 to 300 ng mL^-1 (limit of detection 0.2 pg mL^-1) and 5 pg mL^-1 to 200 ng mL^-1 (limit of detection 0.1 pg mL^-1), respectively. This strategy provides an effective method for high-performance bioanalysis and opens a new door toward the development of the highly sensitive and user-friendly device.