Surface-enhanced Raman scattering using silver nanocluster on anodic aluminum oxide template sensor toward protein...

The affordable surface-enhanced Raman scattering (SERS) substrates, with a structure consisting of densely distributed round-shape silver nanoclusters on anodic aluminum oxide (AAO) template, is fabricated by magnetron sputtering and anodization processes. The physical investigations show that the silver nanoclusters with size distribution ranging from 10 to 30 nm uniformly distributed on the top and in the bottom of the AAO nanochannels. The SERS activities from adsorbed probe molecules, i.e., methylene blue, on the SERS substrate surface indicate a high Raman enhancement factor for trace organic analysis. The SERS substrate is successfully utilized in the detection of a trace amount of three different proteins, bovin serum albumin, immunoglobulin G, and cardiac troponin T, also adsorbed on the substrate surface. Several spectral bands containing important molecular structures of these proteins are clearly observed and identified. The obtained results indicated a step forward to label-free biomolecular detections in chip-based biosensors.