Silica-deposited phospholipid nanotubules as a plausible drug targeting system

An aqueous dispersion of self-organized phospholipid tubules has been utilized as the template for silica-deposited nanotubules (∼0.5 μm thick and >10 μm long) by a sol–gel method. The formation of the hybrid tubules was mechanistically investigated by controlled sol–gel reaction. The incorporation of silica increases the mechanical and thermal stability of tubule geometry. After bioconjugating Ni2+-nitrilotriacetic acid (Ni-NTA) to the surface of chemically modified tubules containing primary amine groups, green fluorescent protein (GFP)-6 His and A33scFv-6 His were further bioconjugated in order to investigate a potential application of these hollow silica tubules as vehicle for targeted controlled release. The resulting tubules bound and internalized to SW1222 endothelial human colon carcinoma cells that express the A33 cell-surface glycoprotein more specifically than HT29 cells that do not express this antigen.