Template synthesis of multifunctional nanotubes for controlled release.

In the past few decades, nanoscale materials have been widely used for controlled release applications. Importantly, many researches have focused on multifunctional nanoparticles for targeted delivery of bioactive and imaging agents as therapeutics and diagnostics. Recent advances in nanotechnology have made possible the design and development of tubular nanoscale particles called nanotubes. The tubular shape of such particles is highly attractive since it is possible to differentially functionalize the inner and outer surfaces to facilitate drug loading, biocompatibility and biorecognition. Novel synthetic strategies allow the fabrication of tubular structures with well-defined diameters and lengths. This can have important implications in biodistribution, subcellular trafficking and drug release. In this article the biomedical applications of nanotubes will be discussed with emphasis on the template synthesis of composite nanotubes containing silica and iron oxide that have potential use in drug delivery, magnetic resonance imaging (MRI), and chemical and biochemical separations.