2.5.1 Components of Nanoemulsion
Basically, a nanoemulsion consists of an active ingredient, an oil phase, surfactant
and aqueous phase. The oil phase is usually the carrier(s) which are mineral oils
and/or vegetable oils (Xu et al. 2011). Today, vegetable oils and their esterified
derivatives are gaining interest compared to the mineral oils because of their
biodegradability and renewability (Xu et al. 2011). Castor oil, copaiba oil, olive oil,
soy oil, Agnique
® AMD 10, Edenol SP 100 is few examples of vegetable oils used
in nanoemulsion formulations. The oil phase in nanoemulsion formulations
enhance the spread and penetration of droplets on the surface of the skin as well as
plants; split open the cuticle to increase both the fluidity of cuticular components
and pesticide diffusion rates (Xu et al. 2011).
2.5.1.1 Surfactants
Surfactants, also called surface-active agents are organic compounds that are
amphiphilic in nature (having both hydrophobic groups and hydrophilic groups)
that reduce surface and interfacial tensions by accumulating at the interface of
immiscible fluids and increase solubility, bioavailability, mobility and subsequent
biodegradation of hydrophobic or insoluble organic compounds (Singh et al. 2011).
They can be found and used as emulsifiers, de-emulsifiers, wetting agents, forming
agents, detergents in petroleum, petrochemicals, functional food ingredients,
environmental management, foods and beverages, agrochemicals, cosmetic and
pharmaceuticals, and in the mining and metallurgical industries (Singh et al. 2011).
Surfactant emulsifiers are added to nanoemusion formulations to ensure spontaneous emulsification with good stability qualities in the spray tank. Surfactants can
be classified as ionic and non-ionic. Non-ionic surfactants are preferred in pesticide
formulation system (Mehmood 2015) than the ionic ones due to their less toxicity,
enhanced solubility, spreading, adsorption, translocation and penetration of active
ingredients into the target. Myers (2005) define non-ionic surfactant as a surfactant
that carries no electric charge, as its water solubility is derived from the occurrence
of polar functionalities capable of significant hydrogen bonding relations with water
(e.g. polyglycidols and polyoxyethylenes) (Shafiq et al. 2007). Although stable
nanoemulsions are best formulated with surfactants or a combination of surfactants
having hydrophile-lipophile balance (HLB) values close to that required for the oil
phase, it is important to know that there are no specified rules to resolve the ratio of
surfactants in the blend surfactants. However, guidance can be obtained from the
(HLB) system.
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Basically, a nanoemulsion consists of an active ingredient, an oil phase, surfactant
and aqueous phase. The oil phase is usually the carrier(s) which are mineral oils
and/or vegetable oils (Xu et al. 2011). Today, vegetable oils and their esterified
derivatives are gaining interest compared to the mineral oils because of their
biodegradability and renewability (Xu et al. 2011). Castor oil, copaiba oil, olive oil,
soy oil, Agnique
® AMD 10, Edenol SP 100 is few examples of vegetable oils used
in nanoemulsion formulations. The oil phase in nanoemulsion formulations
enhance the spread and penetration of droplets on the surface of the skin as well as
plants; split open the cuticle to increase both the fluidity of cuticular components
and pesticide diffusion rates (Xu et al. 2011).
2.5.1.1 Surfactants
Surfactants, also called surface-active agents are organic compounds that are
amphiphilic in nature (having both hydrophobic groups and hydrophilic groups)
that reduce surface and interfacial tensions by accumulating at the interface of
immiscible fluids and increase solubility, bioavailability, mobility and subsequent
biodegradation of hydrophobic or insoluble organic compounds (Singh et al. 2011).
They can be found and used as emulsifiers, de-emulsifiers, wetting agents, forming
agents, detergents in petroleum, petrochemicals, functional food ingredients,
environmental management, foods and beverages, agrochemicals, cosmetic and
pharmaceuticals, and in the mining and metallurgical industries (Singh et al. 2011).
Surfactant emulsifiers are added to nanoemusion formulations to ensure spontaneous emulsification with good stability qualities in the spray tank. Surfactants can
be classified as ionic and non-ionic. Non-ionic surfactants are preferred in pesticide
formulation system (Mehmood 2015) than the ionic ones due to their less toxicity,
enhanced solubility, spreading, adsorption, translocation and penetration of active
ingredients into the target. Myers (2005) define non-ionic surfactant as a surfactant
that carries no electric charge, as its water solubility is derived from the occurrence
of polar functionalities capable of significant hydrogen bonding relations with water
(e.g. polyglycidols and polyoxyethylenes) (Shafiq et al. 2007). Although stable
nanoemulsions are best formulated with surfactants or a combination of surfactants
having hydrophile-lipophile balance (HLB) values close to that required for the oil
phase, it is important to know that there are no specified rules to resolve the ratio of
surfactants in the blend surfactants. However, guidance can be obtained from the
(HLB) system.
2 An Introduction to Bioactive Natural Products …
77