## 2 Nanotechnology and Nanomedicine
### Nanoparticles
Micelles offer an outstanding advantage in drug delivery especially via the oral route thus, protects oral administered insoluble drugs by delivering them to the desired site at the concentration exceeding its intrinsic water solubility [48; 49; 50]. The outer shell, also known as the corona, is the hydrophilic part of the polymer that protects drugs from inactivating in the biological environment while the hydrophobic core sequesters hydrophobic drugs [48; 51]. Encapsulation of drugs within the core are largely dependent on the compatibility between drug molecules and the hydrophobic core which can be estimated by comparing the properties of the hydrophobic segments and that of the polarity of the poorly water soluble drugs [32]. The outer shell serves as a physical shield that stretches its projections outward to prevent micelle-protein or micelle-micelle interactions [46]. Although micelles are considered as delivery vehicles for numerous insoluble drugs [49], they suffer some significant setbacks, thus, limiting their usage as nanocarriers, especially on gene delivery, since they have no convenient method of sequestering and delivering RNA and DNA, and as a result of that, their potential use as a delivery system is hindered [47]. 5. Liposomal Nanoparticles
6. Liposomes are spherical materials representing a perfect model of bio-membranes and cells [52]. They are biocompatible and biodegradable carrier systems. Their structural architecture consists of vesicles which are made up of one or more lipid bilayer with a diameter ranging from 0.02 to 10 \(\upmu\)m or several micrometres [29; 53; 54]. They are the most old prominent and the most widely used nanocarriers that were discovered in the mid-1960s and presently attained their position in modern drug delivery, food industry and gene therapy [55]. The lipid bilayer consists of an aqueous core wrapped by synthetic or natural phospholipids especially phosphatidylcholine but may also include other lipids [50]. Based on the size, number and structure of the lipid bilayer, the liposome is classified into three classes viz; large unilamellar vesicles (LUV), small unilamellar vesicles (SUV) and multilamellar vesicles (MLVs). Encapsulation of hydrophilic, amphiphilic and hydrophobic drugs is done at the aqueous core of the liposomes due to their flexibility hence, solubilisation of insoluble drugs occurs within the phospholipid bilayers [29; 55]. They are abundant with enormous diverse properties such as distinct structures, size, flexibility, physicochemical compositions and variety of surface modifications which promotes them to be efficient carrier systems for both passive and active delivery [29]. They are widely used in food, cosmetics, agriculture and pharmaceuticals industries as a carrier system for safe delivery of materials like genes, drugs and nutraceuticals [52]. They are naturally occurring non-toxic biomaterials that are extremely versatile. Hence, their lipid composition can be manipulated thus, particle size alters alongside surface charge [54]. Some disadvantages of liposome carrier systems are associated with a low transportation rate in vivo as they are rapidly cleared from blood due to the phagocytic activities of the body cells [55]. They are sensitive to temperature, bilayer rigidity and pH. The process of encapsulation has a significant effect on the encapsulation efficiency of liposomes thus; liposomal-drug synthesis holds advantages when there are adequate amounts of drugs and lipids in proportion. However, excessive doses of lipids can interfere with expected pharmacokinetics of the liposomal drugs and sometimes can be toxic [56].