Fluorescent mesoporous silica nanotubes incorporating CdS quantum dots for controlled release of ibuprofen

Mesoporous silica nanotubes (MSNTs) and amine-functionalized MSNTs (NH2-MSNTs) have been successfully synthesized via a sol-gel route using needle-like CaCO3 nanoparticles as inorganic templates and post-modification with 3-aminopropyltriethoxysilane. Subsequently, the preformed nanotubes were functionalized with blue fluorescent CdS quantum dots, as demonstrated by transmission electron microscopy and confocal laser scanning microscopy. The morphology and microstructure of the produced materials were characterized by scanning electron microscopy and N-2 adsorption-desorption measurements. A comparative study of the capacity of several kinds of nanotube materials to store ibuprofen indicated that the drug-loading amount in CdS-NH2-MSNTs (CdS-incorporated NH2-MSNTs) could reach up to 740 mg/g silica, similar to that in as-prepared MSNTs (762 mg/g silica) and NH2-MSNTs (775 mg/g silica). Drug release studies in simulated body fluid revealed that the loaded ibuprofen released from amine-functionalized systems at a significantly lower release rate as compared to that from amine-free systems, and the incorporation of US quantum dots had nearly no effect on the ibuprofen release process. Further study on the ibuprofen release from CdS-NH2-MSNTs in other media, i.e. borate buffer saline, pure water and normal saline, indicated that CdS-NH2-MSNTs are pH- and ion-sensitive drug carriers, which should facilitate controlled drug delivery and disease therapy. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.