3D hybrid arrayed Ag/MOF multi-plasmon resonant cavity system for high-performance SPR sensing

The development of portable biosensors exhibiting outstanding performance for fast and convenient detection of human glucose levels takes on critical significance to human health testing. A two-dimensional metal-organic framework (Cu-TCPP 2D MOF)-sensitized arrayed resonant cavity silver film (ARC/Ag) optical fiber surface plasmon resonance (SPR) sensor was developed in this study. The ARC/Ag 3D structure overcame weak coupling and non-uniform plasmon resonance, and the resulting strong hotspots effectively extended the sensing region. Moreover, the coated MOF is considered as a prominent SPR sensitized layer for its plasmonic property and highly ordered structure. The results of the simulations confirmed the local electric field enhancement that was attributed to the plasmonic synergistic effect of MOF with ARC/Ag. The normalized transmission spectra were collected in ethanol solutions with the refractive index (RI) of 1.340 to 1.352, and the sensitivity and the figure of merit (FOM) of the sensor were demonstrated to be increased by 73.98% and 68%, respectively. The sensor exhibited a linear response factor of 9.99 nm/(mg/mL) over a glucose concentration range of 0.1–1.2 mg/mL by covalently immobilizing glucose oxidase (GOD) on MOF. Accordingly, the proposed highly integrated and portable biosensor provides a piece of promising evidence for label-free glucose detection at point of care (POC).