Implications of Quenching-to-Dequenching Switch in Quantitative Cell Uptake and Biodistribution of Dye-Labeled Nanoparticles

A general strategy to carry out cell uptake and biodistribution studies is to label nanoparticles (NPs) with a fluorescent dye. However, the comparative study of different dye-loaded NPs remains difficult owing to uncontrolled dye quenching and de-quenching. Here we compared two types of dye-labeled NPs and demonstrated their distinct properties. NPs with dye molecules at a solid state suffer from dye quenching, so the dye release and/or NP degradation in biological environments leads to a several-fold increase of fluorescence intensity despite the same amount of NPs, owing to the state switch from quenching to de-quenching. In contrast, NPs with dye molecules at a soluble state exhibit no quenching effect. To standardize the comparative study, we propose two possible solutions: using lower dye loading or using medium analysis for quantifying cell uptake of NPs. This work provides valuable insights into selecting valid quantification methods for bio-nano studies.

Automated summary

This study compared two types of dye-labeled nanoparticles and found that nanoparticles with dye molecules in a solid state undergo dye quenching, while those in a soluble state do not. To standardize the comparative study, the proposed solutions include using lower dye loading or utilizing medium analysis for quantifying cell uptake of nanoparticles. Valuable insights into selecting valid quantification methods for bio-nano studies are provided.