Surface-Enhanced Electrochemiluminescence of Ru@SiO2 for Ultrasensitive Detection of Carcinoembryonic Antigen

Carcinoembryonic antigen (CEA) is recognized as a disease biomarker to reflect the existence of various cancers and tumors in the human body. Sensitive detection of CEA in body fluid is valuable for clinical diagnosis and treatment assessment of cancers. Herein, we present a new approach for ultrasensitive determination of CEA in human serum based on localized surface plasmon resonance (LSPR) enhanced electrochemiluminescence (ECL) of Ru(bpy)32+. In this surface-enhanced ECL (SEECL) sensing scheme, Ru(bpy)32+-doped SiO2 nanoparticles (Ru@SiO2) act as ECL luminophores, and AuNPs are used as LSPR source to enhance the ECL signal. Two different kinds of aptamers specific to CEA are modified on the surface of Ru@SiO2 and AuNPs, respectively. In the presence of CEA, a multilayer of Ru@SiO2–AuNPs nanoarchitectures would be formed. Our investigation reveals that the ECL signal of Ru@SiO2 can be effectively enhanced by AuNPs. One layer of Ru@SiO2–AuNPs nanoarchitectures would generate about 3-fold ECL enhancement compared with the ECL of the nanoarchitectures without the presence of AuNPs. As much as 30-fold ECL enhancement could be obtained by a multilayer of Ru@SiO2–AuNPs nanoarchitectures. Under the optimal conditions, a detection limit of 1.52 × 10–6 ng/mL of CEA in human serum was achieved. To the best of our knowledge, CEA assays with such a low LOD have never been reported for an ECL sensor.