Regeneration of aged-AgNPs via density gradient ultracentrifugal nanoseparation

To reuse aged-silver nanoparticles (AgNPs) and recover the mono-dispersed AgNPs separately, we attempted to recycle the aged-AgNPs with high polydispersity in particle size distribution using the density gradient ultracentrifugation rate (DGUR) separation with five media. Results for the microscopic and spectroscopic showed that Tween series media, which have low density compared to other media, are suitable for the application of DGUR separation for recycling aged-AgNPs. This method might be helpful to regenerate and recycle the precious metal nanoparticles with polydispersity due to long-term storage.