Centrifugation and resuspension of nanoparticle pellets following nanoparticle treatment with protein-containing media remains the most frequently used approach to isolate nanoparticles for analysis. Here, we examined the role of sample isolation using this approach on measured particle characteristics, since it is well known that the centrifugation-resuspension approach for nanoparticle recovery from bulk media, significantly alters nanoparticle physicochemical properties (particle size and concentration) when compared to in-situ sample measurements . Our findings show that (Figure ), there was an increase in mean nanoparticle size for protein-treated nanoparticles following recovery using this method when compared to particles measured within protein-medium. This was most likely due to protein aggregation and particle agglomeration induced by high-speed centrifugation .