Temperature-Induced Protein Release from Water-in-Oil-in-Water Double Emulsions

Abstract

A model water-in-oil-in-water (W1/O/W2) double emulsion was prepared by a two-step emulsification procedure and subsequently subjected to temperature changes that caused the oil phase to freeze and thaw while the two aqueous phases remained liquid. Our previous work on individual double-emulsion globules1 demonstrated that crystallizing the oil phase (O) preserves stability, while subsequent thawing triggers coalescence of the droplets of the internal aqueous phase (W1) with the external aqueous phase (W2), termed external coalescence. Activation of this instability mechanism led to instant release of fluorescently tagged bovine serum albumin (fluorescein isothiocyanate (FITC)-BSA) from the W 1 droplets and into W2. These results motivated us to apply the proposed temperature-induced globule-breakage mechanism to bulk double emulsions. As expected, no phase separation of the emulsion occurred if stored at temperatures below 18 degrees C (freezing point of the model oil n-hexadecane), whereas oil thawing readily caused instability. Crucial variables were identified during experimentation, and found to greatly influence the behavior of bulk double emulsions following freeze-thaw cycling. Adjustment of these variables accounted for a more efficient release of the encapsulated protein.

Enhancing saltiness in emulsion based foods

“…The droplets of the duplex emulsion appear dark due to the enclosed water droplets corresponding to the droplet phase of the initially prepared w/o emulsion. The dark appearance of duplex emulsion droplets has previously been reported in the literature [32][33][34]. The droplet size spectra as well as the d 4,3 values of both types of emulsions compare well and, hence, droplet size can be removed as a variable which may influence saltiness perception.…”

Oil-Frozen W1/O/W2 Double Emulsions for Dermal Biomacromolecular Delivery Containing Ethanol as Chemical Penetration Enhancer

“…W 1 /O/W 2 DEs were prepared by a two-step emulsification procedure as described elsewhere, 40 with a volumetric ratio of 2:2:1. The compositions of the formulations are shown in Table 1.…”

“…38 This instability problem can be overcome by selecting an oil phase, which upon freezing preserves the mechanical stability of the oil globule and its contents, thus preventing mass transport between phases. Subsequent thawing triggers coalescence of the droplets of W 1 with W 2 phase, 39,40 termed external coalescence. [40][41][42][43] DEs have been regarded as suitable carriers for parenteral administration of vaccines, 44 and the shearing of emulsification procedures did not affect significantly the molecular weight 45 or the in vivo antigenicity of antigen.…”

“…Subsequent thawing triggers coalescence of the droplets of W 1 with W 2 phase, 39,40 termed external coalescence. [40][41][42][43] DEs have been regarded as suitable carriers for parenteral administration of vaccines, 44 and the shearing of emulsification procedures did not affect significantly the molecular weight 45 or the in vivo antigenicity of antigen. 46 In fact, upon intramuscular antigen administration, their use showed more effective immune responses when compared with other delivery vehicles such as polymeric nanoparticles.…”

Preparation of stimulus responsive multiple emulsions by membrane emulsification using con a as biochemical sensor

“…Few models of stimuli responsive multiple emulsions are reported in the literature. Temperature-induced release from W 1 /O/W 2 emulsion (Rojas et al, 2008) and pHresponsive pickering emulsion (Li and Stöver, 2008) have been investigated. Biomolecule-responsive emulsions are not yet reported.…”