Gold nanoparticles for sentinel lymph node mapping: Shape-engineered platforms across multimodal imaging

Sentinel lymph node (SLN) mapping is essential for cancer staging and image-guided surgical management, but conventional blue dyes, radiocolloids, and fluorescence tracers remain limited by spatial resolution, penetration depth, and single-modality readouts. Gold nanoparticles (AuNPs) offer a versatile solution because their X-ray attenuation, localized surface plasmon resonance, surface chemistry, and structural tunability support computed tomography, photoacoustic imaging, Raman imaging, nuclear imaging, magnetic resonance imaging, fluorescence, and theranostic functions. This review summarizes shape-engineered AuNP platforms for SLN mapping, including nanospheres, nanorods, nanostars, nanocages, nanoclusters, and hybrid assemblies. We emphasize how particle shape, size, and surface properties govern lymphatic transport, nodal retention, signal generation, immune interactions, and translational feasibility. Finally, current clinical challenges, multimodal design strategies, and safety-oriented pathways for clinical translation are discussed.