Synthesis, Purification, Characterization, and Imaging of Cy3-Functionalized Fluorescent Silver Nanoparticles in 2D and 3D Tumor Models.

Silver nanoparticles (AgNPs) have a high affinity for sulfhydryl (thiol) groups, which can be exploited for functionalization with various tracking and targeting moieties. Here, we describe how to reliably and reproducibly functionalize AgNPs with the fluorescent moiety cyanine3-polyethelyne glycol (5000 molecular weight)-thiol (Cy3-PEG5000-SH). We also demonstrate how to purify and characterize Cy3-functionalized AgNPs (Cy3-AgNPs). Additionally, we describe how these Cy3-AgNPs can be imaged in 2D and 3D tumor models, providing insight into cellular localization and diffusion through a tumor spheroid, respectively.