The top scheme shows the hybridization of nanoparticle probes to complementary single stranded DNA. The length of the probe sequence can be varied to increase discrimination and stability. The Raman reporter (dye) is added to the nanoparticle surface along with the DNA probe sequence to create a unique code for this particular DNA sequence. Schematics (A–C) represent the three different orientations that the probes can take when attaching to a complementary single strand of DNA due to the stereochemistry induced by the deoxyribose sugar on DNA. (A) Tail-to-tail, (B) head-to-tail, (C) head-to-head. Adapted with permission from . Copyright 2015 American Chemical Society.