Label-free plasmonic-based biosensing using a gold nanohole array chip coated with a wafer-scale deposited WS2 monolayer

Abstract

This paper reports the fabrication, testing and obtained performance of a plasmonic sensor employing a gold (Au) nanohole array chip coated with tungsten disulphide (WS₂), which is then functionalized for the detection of protein–protein interactions. A key novelty is that the WS₂ was deposited as a monoatomic layer using a wafer-scale synthesis method that successfully provided a film of both high quality and uniform thickness. The deposited WS₂ film was transferred onto a Au nanohole array chip using a novel method and was subsequently functionalized with biotin. The final sensor was tested and it demonstrated efficient real-time and label-free plasmonic detection of biotin–streptavidin coupling. Specifically, compared to a standard (i.e. uncoated) Au nanohole-based sensor, our WS₂-coated Au nanohole array boosted the spectral shift of the resonance wavelength by ∼190%, resulting in a 7.64-fold improvement of the limit of detection (LOD).