Novel Label‐Free Electrochemiluminescence Immunosensor Based on Ru@SiO ₂ ‐PEI‐Au@Pt Hybrid Nanostructures for Highly Sensitive PSA Detection

A Ru@SiO 2 ‐PEI‐Au@Pt ternary hybrid nanostructure was designed and synthesized to serve as an efficient signal probe for constructing a label‐free electrochemiluminescence (ECL) immunosensor for the ultrasensitive detection of prostate‐specific antigen (PSA). The core innovation lies in the rational design of an integrated nanoplatform with a “luminescent core‐co‐reactant‐catalytic shell” architecture, which enables synergistic signal amplification. Ru(bpy) 3 2+ ‐encapsulated silica nanoparticles (Ru@SiO 2 ) act as stable ECL emitters, where the silica matrix prevents the leakage of Ru(bpy) 3 2+ . Polyethyleneimine (PEI), a polymer with abundant amino groups, serves as an efficient coreactant for Ru(bpy) 3 2+ . Furthermore, to address the limited electrical conductivity of Ru@SiO 2 , Au@Pt nanostructures were introduced as catalytic amplifiers, which not only possess excellent electrical conductivity to promote electron transfer but also exhibit catalytic activity toward the ECL reaction of Ru(bpy) 3 2+ . The synthesis of the Ru@SiO 2 ‐PEI‐Au@Pt nanoparticles was accomplished via electrostatic interaction and/or coordinative bonding between the nitrogen atoms and the Au/Pt centers. The immunosensor was prepared by anchoring anti‐PSA antibodies onto the surface of the Ru@SiO 2 ‐PEI‐Au@Pt nanoparticles. The resulting sensing platform demonstrated a broad linear response for PSA detection over the range of 1 × 10 −11 to 1 × 10 −4 mg·mL −1 , achieving a low detection limit of 6.6 × 10 −12 mg·mL −1 . This work not only provides a robust tool for clinical PSA diagnosis but also offers a generalizable strategy for designing high‐performance ECL nanomaterials by integrating luminescent cores with catalytic shells.