Factors Affecting the Stability and Physical Properties of Pickering Emulsions Stabilized by Fe3 O4 @CNC Nanocomposites

Abstract

Particle-stabilized emulsion systems, namely Pickering emulsions have recently emerged as novel yet attractive dosage form for controlled delivery of biologically active compounds. The stability and properties of emulsions are influenced by formulation and processing factors. In this study, oil-in-water Pickering emulsions were prepared using Fe3 O4 @cellulose nanocrystal (MCNC) nanocomposites and the effects of CNC/Fe3 O4 (CNC/MNP) ratios, MCNC particle concentration Cmcnc, oil volume fraction φoil and ionic strength on the colloidal stability were evaluated. The results showed that stable emulsions could be attained using MCNC particles with CNC/MNP ratio ≤ 1. Increasing CNC/MNP ratio > 1 resulted in different degree of phase separation of emulsions. The average droplet size of MCNC-stabilized Pickering emulsions (MCNC-PE) decreased from 17.34 to 3.58 µm with an increase in Cmcnc as a result of improved coalescence stability due to higher droplet surface coverage Smcnc by MCNC particles. An increase in φoil led to pronounced increase in droplet size from 2.82 to 17.00 µm. Interestingly, the ionic strength showed little or no impact on the emulsion droplet size and creaming. The storage stability study revealed that most emulsions remained fairly stable with no apparent change in droplet size. In conclusion, the physical stability of MCNC-PE was found to be greatly influenced by particulate emulsifier concentration and oil loadings. These two parameters must be well controlled in the development of Pickering emulsions for potential food and pharmaceutical applications.