Uniform and reproducible plasmon-enhanced fluorescence substrate based on PMMA-coated, large-area Au@Ag nanorod arrays

Here we describe a plasmon-enhanced fluorescence substrate based on poly(methyl methacrylate) (PMMA)-coated, large-area Au@Ag nanorod arrays. The use of a PMMA medium enables precise control of the competition between enhancing and quenching processes as a function of the distance between Au@Ag nanorods and dye molecules. At the optimal PMMA layer thickness of 56 nm (for which the distance between nanoparticles and dye molecules is 16 nm), a maximum enhancement of fluorescence of up to ~ 27 times is measured. The competition mechanism between enhancing and quenching processes depends on the thickness of the PMMA layer, which has been confirmed by consistent experimental and theoretical modeling results. Notably, the micropatterned metal-enhanced fluorescence (MEF) substrate exhibits high uniformity and reproducibility. The simple spin-coating process described herein provides an attractive, scalable, and low-cost strategy to produce uniform and reproducible large-area MEF substrates that can potentially be used in many fields, such as biochips, diagnostics, and photonics.