Quantitative surface-enhanced resonant Raman scattering multiplexing of biocompatible gold nanostars for in vitro and ex vivo detection.

Surface-enhanced Raman scattering (SERS)-active plasmonic nanomaterials have become a promising agent for molecular imaging and multiplex detection. To produce strong SERS intensity while retaining the nonaggregated state and biocompatibility needed for bioapplications, we integrated near-infrared (NIR) responsive plasmonic gold nanostars with resonant dyes for resonant SERS (SERRS). The SERRS on nanostars was several orders of magnitude greater than signals from SERRS on nanospheres and nonresonant SERS on nanostars. For the first time, we demonstrated quantitative multiplex detection using four unique nanostar SERRS probes in both in vitro solutions and ex vivo tissue samples under NIR excitation. With further optimization, in vivo tracking of multiple SERRS probes is possible.