MoS2 nanoflowers and gold nanoparticles modified surface plasmon resonance biosensor for sensitivity-improved immunoassay

Biosensors based on surface plasmon resonance (SPR) have shown great applications in drug-screening, environment monitoring, immunoassay, etc., and the sensitivity improvement is one of the prime tasks in the current stage. In this work, taking advantage of the special optical and morphological characteristics of MoS2 nanoflowers, we proposed a sensitivity-improved SPR biosensor by successively depositing MoS2 nanoflowers and gold nanoparticles (AuNPs) onto a traditional SPR sensor, and then applied the biosensor to the immunoassay of mouse IgG. It is found that the deposition of MoS2 nanoflowers can improve the bulk refractive index sensitivity from 2212.2 to 2857.2 nm/RIU (RIU: refractive index unit), but the further addition of AuNPs results in the decrease to 2149.7 nm/RIU. Even so, when it is applied to the IgG immunoassay, the 0.047 nm/(μg/mL) sensitivity of the MoS2-AuNPs-modified sensor shows ~3 times higher than the 0.016 nm/(μg/mL) of the unmodified sensor. The improvement of sensitivity to IgG can be attributed to the flower-like morphology of MoS2 that provides more sites for the loading of AuNPs, thus facilitating the immobilization of a larger amount of IgG antibody on the surface of sensor. Because of the simple fabrication process and the compatibility with the standard bio-activation method on gold surface, the proposed biosensor provides an easily-obtained platform for biological analysis and detection with improved sensitivity.