3D composite SERS substrates with COF spaced Au nanoparticles for enrichment and selective sensitive detection

The excellent performance of surface-enhanced Raman spectroscopy (SERS) is closely related to the intensity, density and uniformity of hotspots. In this study, we introduce a PET/Au NPs@COF Raman substrate featuring three-dimensional hotspots. The spacing between each layer of gold nanoparticles (NPs) is precisely controlled by adjusting the thickness of the COF via the interfacial synthesis technique, causing the strong coupling between gold particles across the layers. The porosity of the COF enables the substrate to adsorb numerous analyte molecules into the large-area uniform hotspots. Through simulations and adsorption detection on the substrate, Raman testing further demonstrated that the substrate with double-layer Au NPs@COF exhibited the most favorable SERS performance. Additionally, the substrate allows for selective detection based on the particle size of the target molecule. The flexibility of the substrate enables it to conform to irregular surfaces, effectively capturing analytes from a variety of real samples.