SERS-based recyclable immunoassay mediated by 1T-2H mixed-phase magnetic molybdenum disulfide probe and 2D graphitic carbon nitride substrate

Recently, non-metallic SERS-based immunoassay has attracted much attention due to its attractive chemical enhancement (CM), chemical stability, and biocompatibility. Herein, metallic (1T)-semiconductor (2H) mixed -phase magnetic molybdenum disulfide (MoS2) was rationally developed and combined with two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets to realize a SERS-based recyclable immunoassay of CA125. The Fe3O4 core promoted the reliable stacking of MoS2 nanoflakes into a flower-like shape with fully-exposed active surface. Particularly, the existence of 1T phase facilitated a noble-metal-comparable SERS activity due to the high electron density-induced charge transfer process with elevated efficiency. Moreover, a conversion from bulk to 2D nanosheet was swimmingly achieved for g-C3N4 via acid etching, whose large surface area full of active electrons and functional groups triggered an enhancement factor (EF) of 7.8 x 106. Based on a typical sandwich immunostructure, a limit of detection (LOD) as 4.96 x 10-4 IU/mL was demonstrated for CA125 in a recyclable process. Finally, such an immunosensor was employed to analyze clinical samples, indicating its prodigious potentiality in the early recognition and monitoring of cancer.

Automated summary

Recently, non-metallic SERS-based immunoassay using mixed-phase magnetic MoS2 and g-C3N4 nanosheets has been developed for the recyclable detection of CA125. The addition of Fe3O4 core promotes the stacking of MoS2 nanoflakes, while the presence of 1T phase enhances the SERS activity. Acid etching converts g-C3N4 to a 2D nanosheet with a high surface area, leading to a significant enhancement factor. The immunosensor shows a limit of detection of 4.96 x 10-4 IU/mL for CA125 and demonstrates great potential in cancer recognition and monitoring.