Components required for the formation of niosomes
The two major components used for the formation of niosomes are:
Non-ionic surfactant
Cholesterol
Non-ionic surfactant
Non-ionic surfactants play a major role in niosomal formulations. The surfactant used must have a hydrophilic head and a hydrophobic tail. The hydrophobic moiety may consist of 1 or 2 alkyl or perfluroalkyl groups or in certain cases a single stearyl group. The surfactants with alkyl chain length from C12-C18 are suitable for preparation of noisome [33].
The most commonly used surfactants are given in Table 2 [34]:
Table 2 List of Non-ionic surfactants of various types.
Types of non-ionic surfactant Examples
Fatty alcohol Cetyl alcohol, Stearyl alcohol, Cetostearyl alcohol, oleyl alcohol
Ethers Brij, Lauryl glucoside, Decyl glucoside, Octyl glucoside, Triton X-100
Esters…show more content… The incorporation of cholesterol into bilayer of niosome induces membrane stabilization and decreases the leakiness of membrane. Thus, it increases the entrapment efficiency of niosomes [30]. Many surfactants can form vesicles after the addition of cholesterol in concentrations of up to 30–50 mol% [35]. Cholesterol being an amphiphilic molecule interacts with surfactants through hydrogen bonding between its hydroxyl group and surfactant’s hydrocarbon chain which leads to an increase in the mechanical stiffness of the membranes and membrane cohesion. Cholesterol also has a condensing effect as it accommodates in the cavity which is formed by surfactant monomers. This is known as space filling function of cholesterol due to which the movement of carbons of hydrocarbon is restricted which leads to a decrease in the permeability of cholesterol containing membranes as compared to cholesterol free membranes. Also cholesterol increases the surface elasticity of membranes making them more rigid in nature