An unmet clinical need exists for accurate, dynamic, and noninvasive diagnostic tools that addresses the limitations of current approaches, and enables multiplexed detection of both PD-L1 and CD8+ T cells in vivo.  This research addresses this need with immunoactive gold nanoparticles (IGNs), an innovative multimodal probe that seamlessly integrates the merits of immuno-PET with surface-enhanced Raman spectroscopy (SERS).  SERS, an optical technique, uses near-infrared (NIR) light to enhance the vibrational signal of Raman reporters enabling narrow spectral features amenable for multiplexing.  The successful integration of PET with SERS in a multimodal nanoprobe will provide a validated tool for real time immunological profiling that will ultimately identify targetable pathways to improve immunotherapies and patient outcomes.