In this paper, we have designed and fabricated an atomically thin plasmonic sensing substrate based on two-dimensional phase change material Ge2Sb2Te5 and silver (Ag-GST). This substrate offers an ultra-low reflection in the SPR curves and a strong optical phase singularity. A custom-built SPR setup was developed here to directly measure the phase-singularity-induced lateral position shift. We have obtained a SPR sensitivity regarding the lateral position shift of 9.9577 x 10^7 μm/RIU, which is 3 orders of magnitudes higher than current position shift sensing scheme based on hyperbolic metamaterial. Due to the ultra-high SPR sensitivity, the binding processes between peptide and integrins directly from un-purified liposomes were real-time monitored. The concentrations of Mn2+ ions ranging from 1 fM to 1 mM on the binding dynamics have been systematically monitored with our developed phase-sensitive surface plasmon resonance biosensors.
In this study, we report the design of a 2D nanomaterial-enhanced biosensor by integrating both the 2D nanomaterials and immunoassay sensing techniques. A phase interrogation surface plasmon resonance (SPR) system was used for detecting antigen with a concentration ranging from nanomolar to femtomolar level. Our work has shown that the evanescent field generated from the Au film to 2D perovskite could lead to a significant sensitivity improvement. This specially antibody-functionalized sensing substrate, embedded with plasmonic metasurface structure, exhibited strong plasmonic coupling effect. And this optimized nanostructure could be engineered as a powerful and ultrasensitive platform for cancer diagnostics. The thickness of the sensing substrate is tuned in an atomic scale and optimized to obtain an enhanced sensing effect. More specifically, a sharp phase signal change and phase-related Goos-Hänchen signal shift was achieved that results from the strong resonance. The improved sensitivities of 2D Perovskite nanostructures were investigated. It is worth noting that the atomic layer design led to the sensing substrate optimized with a tuning scale less than 1 nm. Through a precise engineering of the metasurface substrates, 3 orders of magnitude improvement of the sensitivity (800,000 um/RIU) were demonstrated compared to the one with pure gold sensing substrate (300 um/RIU). This hybrid 2D nanomaterial-based metasurfaces would provide a good opportunity for the development of integrated cancer theranostic devices.
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