Synthesis and Application of CeO2/SnS2 Heterostructures as a Highly Efficient Coreaction Accelerator in the Luminol–Dissolved O2 System for Ultrasensitive Biomarkers Immunoassay

Electrocheluminescence (ECL) immunoassay amplified by coreaction accelerators has experienced major breakthroughs in ultrasensitive detection of biomarkers. Herein, CeO2/SnS2 heterostructures were synthesized and applied as a novel coreaction accelerator to enhance the ECL efficiency of the luminol–dissolved O2 system for the first time. Benefiting from the well-matched lattice spacing, ultrafine CeO2 nanoparticles (NPs) were grown in situ on layered SnS2 nanosheets (NSs) with improved dispersion. CeO2/SnS2 as an electroactive substrate can remarkably accelerate the generation of abundant superoxide anion radicals (O2•–) to react with luminol anion radical (L•–), achieving about 2-fold stronger ECL intensity than that of pure CeO2 NPs. To avoid harsh chemical synthesis of conventional ECL labels and simplify the antibody conjugation process, ferritin (Ft) was served as a natural nanocarrier to immobilize luminol molecules (Lum@Ft) via a one-step linkage, whose protein nanocage can easily connect with the detection antibody. Moreover, a robust site-oriented immobilization strategy using HWRGWVC heptapeptide as specific capturer was further adopted to maintain the bioactivity of the capture antibody on the amine-functionalized CeO2/SnS2 surface, which promoted the incubation efficiency markedly. On account of this advanced sensing strategy, a brand new biosensor was constructed for the accurate detection of heart failure biomarkers, which performed with favorable linearity in the range of 0.0001–50 ng/mL and achieved the detection limit of 36 fg/mL.