Dual-Labelled Nanoparticles Inform on the Stability of Fluorescent Labels In Vivo

Fluorescent labelling is commonly used to monitor the biodistribution of nanomedicines. However, meaningful interpretation of the results requires that the fluorescent label remains attached to the nanomedicine. In this work, we explore the stability of three fluorophores (BODIPY650, Cyanine 5 and AZ647) attached to polymeric hydrophobic biodegradable anchors. Using dual-labelled poly(ethylene glycol)-b-poly(lactic acid) (PEG-PLA) nanoparticles that are both radioactive and fluorescent, we investigated how the properties of the fluorophores impact the stability of the labelling in vitro and in vivo. Results suggest that the more hydrophilic dye (AZ647) is released faster from nanoparticles, and that this instability results in misinterpretation of in vivo data. While hydrophobic dyes are likely more suitable to track nanoparticles in biological environments, quenching of the fluorescence inside the nanoparticles can also introduce artefacts. Altogether, this work raises awareness about the importance of stable labelling methods when investigating the biological fate of nanomedicines.

Automated summary

Fluorescent labelling is commonly used to monitor the biodistribution of nanomedicines, but the stability of the labelling is crucial for meaningful interpretation of the results. This study investigates the stability of three fluorophores attached to polymeric hydrophobic biodegradable anchors. Results suggest that the more hydrophilic dye is released faster from the nanoparticles, leading to misinterpretation of in vivo data. These findings highlight the importance of stable labelling methods when studying the biological fate of nanomedicines.