Monitoring the interfacial release rate of resveratrol in Pickering emulsions stabilized by cellulose nanocrystals through the control of the surface coverage

Abstract

Pickering emulsions (PE) are emulsions stabilized by particles, rather than surfactants like conventional emulsions. This gives them numerous advantages, such as greater stability, reduced toxicity and a tighter drop size distribution. These are just some of the reasons why PEs are booming, particularly in the field of drug delivery. Controlling the release of the active ingredient is thought to depend on the coverage of the emulsion surface by the particles (C). This work first shows how to control C in the case of hexadecane-in-water emulsions stabilized by cellulose nanocrystals (CNCs). It decreases linearly with the salt (NaCl) concentration of the aqueous medium. When resveratrol (RSV), a hydrophobic model molecule, is incorporated into the hexadecane, with an uptake up to 98 ± 3%, this dependence is lost in favour of a dependence, again linear with RSV concentration. By modelling the release of RSV incorporated into PE of different C, we have demonstrated that k1, the interfacial rate constant of RSV, is controlled by C. CNCs on the droplet surface slow down the release of encapsulated RSV, the higher the droplet surface coverage.