Nanodisk codes.

We report a new encoding system based upon dispersible arrays of nanodisks prepared by on-wire lithography and functionalized with Raman active chromophores. These nanodisk arrays are encoded both physically (in a "barcode" pattern) and spectroscopically (Raman) along the array. These structures can be used in covert encoding strategies because of their small size or as biological labels with readout by scanning confocal Raman spectroscopy. As proof-of-concept, we demonstrate their utility in DNA detection in a multiplexed format at target concentrations as low as 100 fM.