Freeze-drying of silica nanoparticles: redispersibility toward nanomedicine applications.
AIM
To study freeze-drying of silica nanoparticles (SiO2NPs) in order to find suitable conditions to produce lyophilized powders with no aggregation after resuspension and storage.


METHODS
SiO2NPs were synthesized using a Stöber-based procedure, and characterized by scanning electron microscopy, dynamic light scattering and nitrogen adsorption/desorption isotherms. SiO2NPs hydrodynamic diameters were compared prior and after freeze-drying in the presence/absence of carbohydrate protectants.


RESULTS
Glucose was found to be the most suitable protectant against the detrimental effects of lyophilization. The minimum concentration of carbohydrate required to effectively protect SiO2NPs from aggregation during freeze-drying is influenced by the nanoparticle's size and texture. Negligible aggregation was observed during storage.


CONCLUSION
Carbohydrates can be used during SiO2NPs freeze-drying process to obtain redispersable solids that maintain original sizes without residual aggregation.