Nanographene-Based Polymeric Nanoparticles as Near-Infrared Emissive Neuronal Tracers

Precise tracking of axonal transport is key to deciphering neuronal functions. To achieve long-term imaging at both ultrastructural and macroscopic resolutions, it is critical to develop fluorescent transport tracers with high photostability and biocompatibility. Herein, we report the investigation of nanographene (NG)-based polymeric nanoparticles (NPs) as near-infrared (NIR)-emissive neuronal tracers. Dibenzo[<i>a</i>,<i>m</i>]dinaphtho[3,2,1-<i>ef</i>:1',2',3'-<i>hi</i>]coronene (DBDNC) was employed as the NG, which exhibited a broad NIR emission with a maximum at 711 nm inside the NPs. DBDNC-NPs displayed high photostability and low cytotoxicity, enabling live tracing of retrograde axonal transport in mouse sensory neurons cultured in microfluidic chambers. We also elucidated how DBDNC-NPs undergo retrograde axonal transport following the endolysosomal pathway. This work provides a proof of concept for NIR-emissive, NG-based neuronal tracers with potential for applications in neurobiology.