Boron nitride quantum dots as electrochemiluminescence coreactants of rGO@Au@Ru–SiO2 for label-free detection of AFP in human serum

Abstract

A label-free electrochemiluminescence (ECL) immunosensor is developed to detect alpha-fetoprotein (AFP). Ru (bpy)32+-doped silica nanoparticles (Ru–SiO2) and gold nanoparticle-modified reduced graphene oxide (rGO@Au) are integrated to form an rGO@Au@Ru–SiO2 composite. The composite is employed as a carrier for immobilizing the target antibody, and a label-free ECL immunosensor is constructed via antigen–antibody interaction. Owing to the numerous Ru (bpy)32+ molecules in the Ru–SiO2, a high ECL signal is acquired. With excellent conductivity and a large surface area, the rGO@Au composite not only accelerates electron transfer but also improved the ECL signal and captures antibodies, thus enhancing ECL response and sensitivity. Moreover, boron nitride quantum dots (BNQDs) are used as rGO@Au@Ru–SiO2 coreactants, achieving high ECL intensity. The proposed ECL system exhibits significant potential in bioanalysis, which is attributed to the excellent biocompatibility and good stability of BNQDs. Under optimal experimental conditions, the sensor has a linear range of 0.0001 ng mL−1 to 100 ng mL−1 and a limit of detection equal to 0.03 pg mL−1 (S/N = 3). The proposed technique is successfully applied in the susceptible detection of AFP in human serum. The recovery ranges from 99% to 100%, and the RSD is less than 2.8%. The constructed ECL immunosensor exhibits acceptable performance during actual application.