Ultrasensitive electrochemiluminescent immunosensor using MoS₂/g-C₃N₄ nanosheets

In this work, graphite-like carbon nitride nanosheets (g-C₃N₄) coupled with layered MoS₂ were synthesized via a direct mixing and calcination method. Then they were studied as a new type of highly efficient luminescent material in an electrochemiluminescent (ECL) immunosensor. The prepared g-C₃N₄/MoS₂ nanosheets exhibited strong and stable cathodic ECL activity compared to individual g-C₃N₄ and MoS₂. One possible reason is that the synergy between the g-C₃N₄ and MoS₂ would promote charge transfer and, thus, enhance the separation efficiency of electron-hole pairs. In addition, the combination also mitigates the passivation of g-C₃N₄. The ECL assay for alpha-fetoprotein (AFP) detection by using g-C₃N₄/MoS₂ nanosheets was developed with excellent sensitivity at wide concentration ranges from 0.001 to 50 ng/mL. The limit of detection (LOD) is also down to 0.33 pg/mL, which is superior to other materials. Importantly, the designed immunosensor exhibited excellent selectivity, reproducibility, and long-term stability. The MoS₂/g-C₃N₄ nanocomposite-based immunosensor is also promising for medical diagnosis.