O/W/O Multiple Emulsions via One‐Step Emulsification Process

Abstract

The preparation of O/W/O multiple emulsions by a one-step emulsification process was studied using an optical microscope equipped with a camera. The O/W/O multiple emulsions could be prepared by the introduction of two surfactants and two polymers. But when one of two polymers or water-soluble surfactant was not added, W/O emulsions with various size distributions were formed. Tween 20 added in water destabilizes W/O interfacial films formed by Span 80. At a result, the diffusion of 1-octanol into water droplets occurred more easily. Using a polymer in the continuous phase, the swelling of W/O interfaces was retarded but the use of two polymers in the continuous and discontinuous phases assisted the micelles mixed with oil molecules to diffuse into the core of aqueous droplets and remain. Moreover, the interaction between Tween 20 and PEG promoted coalescence of oil-swollen micelles in the water droplets. Depending upon the choice of water-soluble nonionic surfactants and polymers, three types of emulsion droplets were observed. Variation in the shapes of the droplets was due to differences in solubilization power of the surfactants. Also, the O/W/O multiple emulsions were stable for 8 h but most of the emulsions were at least partially broken after 24 h.

Influence of Phase Inversion on the Formation and Stability of One-Step Multiple Emulsions

“…Multiple emulsions are complex and heterogeneous systems in which both types of simple emulsions (oil-in-water (O/W) and water-in-oil (W/O)) coexist simultaneously, forming either water-in-oil-in-water (W/O/W) or oil-in-water-in-oil (O/W/O) emulsions in the presence of two stabilizing surfactants, one hydrophilic and another lipophilic. − They have potential applications as pharmaceutical and cosmetic delivery vehicles because of their ability to entrap and slowly release different agents. − However, their use has been restricted because of their intrinsic instability and complex structure. ,− Consequently, a systematic investigation of the effects of different process and composition parameters such as (i) type of the oil phase, (ii) type of emulsifying agents, (iii) phase volume ratio, (iv) hydrophilic/lipophilic surfactant ratio, and (v) process variables (e.g., emulsification temperature and agitation speed) on emulsion formation and stability is necessary if multiple emulsion formulation is to be considered . Moreover, such a systematic study will contribute not only to our understanding of multiple emulsions, but also emulsion systems in general, from both a practical and theoretical point of view …”

“…The two-step method is complex and introduces possible destabilization pathways (e.g., solubilization of the primary surfactant may take place as a result of the excess surfactant that is typically introduced in the re-emulsification step, and osmotic pressure differences between theinternal and external water phases are often created). , Such destabilization pathways can be avoided when the one-step method is used. In addition, the one-step emulsification method is more efficient in terms of time and production cost. ,,, …”

Current Status of Research on Kidney and Psychiatric Disorders (Dementia as an Example)

“…Therefore, it can be seen that "the kidney is the master of ambition" is also related to neuropsychological aspects to a certain extent. Recognizing that the kidney is the master of ambition from the perspective of modern psychology enriches the connotation of Chinese medicine, and provides a theoretical basis for the treatment of psychiatric disorders from the perspective of the kidney [4].…”

Recent progress in oil-in-water-in-oil (O/W/O) double emulsions

“…Besides, one-step phase inversion was also reported to be a feasible strategy for the formulation of O/W/O emulsions, the mechanism of which was suggested to be attributed to the diffusion of oil from the continuous external phase to the inner phase (Figure 2b). Using this one-step method, Oh et al (2004) fabricated one kind of O/W/O emulsion system, in which Span 80 was working as a lipophilic emulsifier toward formulation of the W/O emulsion. When Tween 20 was added into the water phase, the stable W/O interface would be out of balance, in turn accelerating the diffusion of the oil phase (1-octanol) into water droplets.…”