Integrating the amino-functionalized MOF-5 film with the silver nanoparticle substrate for a high SERS enhancement effect and long-term stability

Abstract

Plasmonic has sparked a lot of interest in customizing localized surface plasmon resonance for new biosensing approaches. We report experimental results that highlight the mechanisms underpinning the combined electromagnetic and chemical contributions of surface-enhanced Raman scattering. The amino-functionalized metal–organic framework-5 (MOF-5-NH₂) platforms were demonstrated to have the ability to enhance Raman scattering through sensitivity with molecular Raman probes such as rhodamine B (RhB) and methylene blue (MB). This multi-component substrate allows for the detection of molecules at low concentrations as low as 1.78 × 10⁻¹⁰ M of MB and 1.26 × 10⁻¹² M of RhB, with the following durability and stability SERS signals after 120 days of storage. The plasmon excitations of the double-layer substrates caused a resonant increase in Raman scattering, recording an approximately 13-fold increase in signal amplification after the deposition of a 3D structure layer on the silver single-membrane substrate. The location of the porous outer layer on the plasmonic surface increases the in situ molecular density, reducing the distance between the SERS-active region and the molecules responsible for molecule manipulation near hotspot engineering. Our findings provide a general framework for investigating the contribution of metal nanomaterials (NPs) and metal–organic frameworks to SERS, as well as for improving the Raman efficiency of Ag NP templates through deposition modification using MOF-5-NH₂ films. This innovative approach paves the way for SERS platforms on ultrasensitive substrates and biosensing applications.