Silver-Based Nanodisk Codes

We report a novel method for synthesizing silver-based nanodisk code (NDC) structures using on-wire lithography, where we employ milder synthetic and etching conditions than those used to synthesize the analogous gold structures. The silver structures exhibit stronger surface-enhanced Raman scattering signals than their Au counterparts at 633 and 532 nm excitation and, therefore, lead to lower limits of detection when used in the context of DNA-based detection assays. Finally, use of two enhancing nanostructured materials in one disk code dramatically increases the information storage density for encoding. For example, a disk code consisting of 5 gold disk pairs has 13 unique combinations of enhancing patterns, while one with 5 disk pairs that can be either gold or silver has 98.