Mesoporous silica tubular nanocarriers for the delivery of therapeutic molecules

Abstract

Nanocarriers to load and deliver biomolecules are promising platforms to improve the therapeutic efficacy of the molecules. Here, we report a novel inorganic mesoporous nanotubular carrier made of silicate as an effective delivery system for biomolecules including chemical drugs, proteins and genes. Silicate hollow nanotubes were replicated from carbon nanotubes via a sol–gel process and heat-treatment. In particular, mesopores were generated within the silicate nanotubes to provide a space for the loading of therapeutic molecules. While the surface of the as-prepared mesoporous silica nanotube (mSiNT) was highly negative (−28 mV), an amine-functionalization made the surface highly positive (+32 mV), which provided a switchable platform for selective loading of molecules depending on the surface charge characteristics. As model drugs, sodium-ampicillin, cytochrome C and small interfering RNA (siRNA) were employed to investigate the loading capacity of, and release profile from, the mSiNT. The molecules were loaded onto mSiNTs selectively, taking into account their molecular charge. The mSiNTs were capable of incorporating the therapeutic molecules in a way that was highly dependent on the level of mesoporosity. The loaded ampicillin and cytochrome C were released for a relatively short period (i.e., within 2 days). The siRNA was also easily complexed with the aminated-mSiNTs, and was released for a prolonged period of up to ∼7 days. When the mSiNT–siRNA complex was delivered to HeLa cells, the transfection efficiency was approximately 56%, and the siRNA silencing effect assessed by bcl-2 was also evidenced. Based on this study, the nanotubular form of mesoporous silica is considered as a potential non-viral delivery vehicle for a range of therapeutic molecules.