Figure 1: Drug encapsulated transport of multi-ligand targeted nanoparticles. The transport of molecules through the bood brain barrier (BBB) is mediated through different mechanism (A). These include (i) transcellular diffusion which depends on the lipophilicity and size of molecules, (ii) transporter protein mediated endocytosis, primarily used in the delivery of nutrients, (iii) paracellular diffusion of hydrophilic and small moleculaes through tight juctions of epithelial cells, (iv) receptor mediated endocytosis, enabling the transport of various molecules such a genes, proteins and targeted nanoparticles and (v) absorptive transport depending on the surface charge of molecules. (B) Nanoparticels trasported through the BBB, targets specific neuronal cells due to the presence of cell specific targeting ligands. Multi-functional nanoparticles can be used to detect tumours via MRI [154] (C) and simultaneously induce cell death by releasing chemotherapeutic drugs (D).