An Update on Nanoemulsions Using Nanosized Liquid in Liquid Colloidal Systems

Abstract

Nanoemulsions, kinetically stable and thermodynamically unstable colloidal liquid-in-liquid dispersions with droplet sizes in the order of 20-500 nm mainly consist of oil, surfactants, co surfactants and an aqueous phase. There are various methods for the fabrication of Nano-emulsions which can be divided based on the energy required-High energy emulsification methods and Low energy emulsification methods. High energy emulsification includes methods like Ultra sonication, high pressure homogenization using either microfluidizers or high-pressure homogenizers. Low energy emulsification has drawn attention since they are soft, nondestructive and cause no damage to encapsulated molecules and includes methods like phase inversion temperature, solvent displacement, phase inversion composition method. Nanoemulsions are best suited for drug delivery systems because of their lipophilic nature, optical clarity and surface area. Owing to their nature to prevent flocculation and inherent creaming, nanoemulsions find an important place in the cosmetic industry also. This chapter provides an insight into the use of nanogels, emulsion based wet wipes and PEG free nanoemulsions in cosmetics. In the food industry, nanoemulsions are utilized for the production of functional foods. Some of the patented nanoemulsions and their commercial applications have also been mentioned.

Perspective Chapter: Microemulsion as a Game Changer to Conquer Cancer with an Emphasis on Herbal Compounds

“…Suppose when there is an increase in temperature, it leads to the water in oil microemulsion, whereas when the temperature decreases it leads to oil in water microemulsion [24]. While coming to the phase inversion composition, the addition of the water or oil makes the difference [25].…”

Biodegradable Amphoteric Surfactants in Titration-Ultrasound Formulation of Oil-in-Water Nanoemulsions: Rational Design, Development, and Kinetic Stability

“…The role of the surfactant is to lower the surface tension by preferential adsorption at the oil/water interface, providing a mechanical barrier to coalescence, flocculation, or other destabilization processes of a given formulation. Thus, the selection of appropriate emulsifiers is essential in controlling the functional properties of nanoemulsions, including surface charge, droplet size, their polydispersity, and their long-term (kinetic) stability [1,4,9,25].…”

“…In the case of system 6 with 5% LA/2% CAPB, the droplet size exceeded 300 nm, but the PdI did not exceed 0.3. However, the larger droplet size may make such a system more susceptible to nanoemulsion destabilization processes such as flocculation, coalescence, sedimentation, or creaming [9,11]. Thus, only the most unimodal nanoformulations (darkened lines in Table 1) with the optimized composition and size parameters (D H 100-300 nm, PdI < 0.3) were selected for further dispersion stability investigations.…”

“…It has been proven that long-term stable NEs characterized by a high value of the ζ-potential are effectively stabilized by electrostatic repulsion. When this potential is low (0 to ±5 mV), the attraction of the dispersion droplets exceeds their repulsion, and the nanoemulsion is rapidly destabilized by processes such as coagulation and flocculation [1,9]. Thus, it is necessary to assess the ζ-potential magnitude of the studied formulations to identify the charge of oil droplets in the NE systems and to predict their stability.…”

“…They are transparent or translucent isotropic dispersions consisting of two immiscible water and oil phases. One of these liquids is dispersed in the other through a suitable surfactant mixture, forming a colloidal nanosystem [9]. Due to the possibly identical droplet size and subsequently numerous inaccuracies in the scientific literature, NEs are often confused with thermodynamically stable microemulsions (10-100 nm).…”