Fabrication of Ag Nanorods on Micropost Array for a Metal-Enhanced Fluorescence Substrate with a High Signal-to-Background Ratio
Ag nanorods on micropost array (AgNMPA) was fabricated by the UV-imprinting process and the glancing angle deposition (GLAD) technique as a metal enhanced fluorescence substrate with improved signal-to-background noise ratio (SBR). Micropost structures (50 μm in height, 300 μm in diameter, and 600 μm in pitch) were replicated on glass slides by UV imprinting, and an Ag nanorod structures were formed on top of the micropost structures using GLAD. To maximize the SBR of the proposed AgNMPA MEF substrate, the effects of deposition angles during the GLAD process on the measured fluorescence intensity and SBR of AgNMPA MEF substrates were examined. As a reference, the bare glass substrate and GLAD MEF substrate having GLAD Ag nanorods on bare substrate were fabricated. For fluorescence signal measurement, myeloid progenitor inhibitory factor 1 (MPIF-1) capture antibodies were spotted onto each substrate after amine treatment and their fluorescence intensity were measured after the antibody-antigen reaction. The 71x enhanced fluorescence intensity comparing to the bare glass substrate was obtained from the optimum AgNMPA MEF substrate that had a substrate rotation speed of 5 rpm, d angle of 89°, deposition rate of 0.5 nm/s, and deposition thickness of 500 nm. The SBR of the optimum AgNMPA MEF substrate was 41.0, which was 7 times greater than that form the GLAD substrate and 25 times greater than that from the bare glass substrate.