Freeze-drying of silica nanoparticles: redispersibility toward nanomedicine applications

Aim: To study freeze-drying of silica nanoparticles (SiO(2)NPs) in order to find suitable conditions to produce lyophilized powders with no aggregation after resuspension and storage. Methods: SiO(2)NPs were synthesized using a Stober-based procedure, and characterized by scanning electron microscopy, dynamic light scattering and nitrogen adsorption/desorption isotherms. SiO(2)NPs 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 SiO(2)NPs 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 SiO(2)NPs freeze-drying process to obtain redispersable solids that maintain original sizes without residual aggregation. (AU)