Table 1.

Different types of drug delivery system.

Drug delivery system	Structure	Chemical properties	References
Liposomes		Consists of hydrophobic tail and hydrophilic head group	27–29
		Forms closed vesicles with an aqueous core
		Internal aqueous domain between the lipid bilayers
		Encapsulation of drugs occurs either in the aqueous space or intercalated into the bilayer
Dendrimers		Hyper branched and globular macromolecules	30–32
		Well defined core, backbone and multivalent periphery
		By hydrophobic and electrostatic interactions, incorporate biomolecules
		Convergent – endo-receptor
		Divergent – exo-receptor
Carbon nanotubes		Rolling up a single layer of grapheme sheet – single walled	33–37
		Rolling up many layers to form concentric cylinders – multi-walled
Gold nanoparticles		Gold nanoparticle serves as core	8,38
		Photosensitive
Iron oxide nanoparticles		Superparamagnetic particles	8,39
		Need trigger to release biomolecules, for example, laser irradiation
Titanium dioxide nanoparticles		Self-ordered	40–42
		Nano-tubular structure
		Photodynamic therapy
Silica nanoparticles		Mesoporous structure	7, 23, 25
		Honeycomb-like structure
		Active surface