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.