Mesoporous silica encapsulation of silicon nanocrystals: Synthesis, aqueous dispersibility and drug release

• We found a new method to disperse hydrophobic silicon nanocrystals (Si-NCs) in aqueous media by encapsulating within high surface area mesoporous silica nanospheres.
• Using energy-filtered transmission electron microscopy we found that a single Si-NC was encapsulated within each mesoporous silica nanosphere.
• The resulting multifunctional materials retain their near-IR photoluminescence and can be well dispersed in aqueous media.
• Proof-of-concept drug release using ibuprofen was demonstrated, showing a significant amount of ibuprofen could be loaded into the mesopores and slowly released over a timescale of days.

Silicon nanocrystals (Si-NCs) are of significant research interest because of their tunable photoluminescent properties and biological compatibility. We have encapsulated Si-NCs within a high surface area mesoporous silica shell while maintaining the NC near-IR photoluminescence. This material is a potential platform for combined biological imaging and drug delivery. Encapsulation of a single crystalline Si-NC within each nanosphere is shown using energy-filtered transmission electron microscopy. Proof-of-concept drug delivery studies show ibuprofen release from the nanospheres.