Pickering emulsions, stabilised by organic or inorganic particles, offer long-term dispersibility of liquid droplets and resistance to coalescence. The versatility of stabilising particles and their ability to encapsulate and release cargo with high internal payload capacity makes them attractive in a wide variety of applications, ranging from catalysis to the cosmetic and food industry. While these properties make them an equally promising material platform for pharmaceutical and clinical applications, the development of Pickering emulsions for healthcare is still in its infancy. Herein, we summarise and discuss recent progress in the development of Pickering emulsions for biomedical applications, probing their design for passive diffusion-based release as well as stimuli-responsive destabilisation. We further comment on challenges and future directions of this exciting and rapidly expanding area of research.Pickering emulsions have been applied in a number of areas of research and industrial importance, such as food manufacturing, cosmetics, agrochemicals and therapeutic delivery. Their popularity in biomedical applications (i.e. for use in healthcare, such as therapeutics, diagnostics or imaging), in particular, has increased dramatically in recent years, thanks to their high stability, capacity for superior cargo loading compared to conventional systems, and diverse range of stabilising particles, creating a broad library of available building blocks. For biomedical and pharmaceutical application, the choice of emulsifier is critical; it must be biocompatible, non-toxic, and be able to be excreted from the body (if necessary). In this article, we will review the latest developments in the design and application of Pickering emulsions for biomedicine, with a focus on stimuli-responsive Pickering emulsions as a route to the triggered release of a payload towards advanced therapeutic delivery strategies. Within this discussion, we will describe systems which have been applied in proof of concept and in vitro assessments and emphasise areas of potential future development.

The controlled formation of microdroplets through temperature variation is an intriguing concept for binary liquid mixtures with a critical solution temperature. Here, we investigate this phenomenon for a blend of...

Three sterically-enhanced 2-imino-6-(1-naphthyl)pyridines, 2-{CMe=N(Ar)}-6-(1-C10H7)C5H3N [Ar = 2,6-i-Pr2C6H3 (L1dipp), 2,4,6-i-Pr3C6H2 (L1tripp), 4-Br-2,6-i-Pr2C6H2 (L1Brdipp)], differing only in the electronic properties of the N-aryl group, have been prepared in high yield by the condensation reaction of 2-{CMe=O}-6-(1-C10H7)C5H3N with the corresponding aniline. Treatment of L1dipp, L1tripp and L1Brdipp with two equivalents of AlMe3 at elevated temperature affords the distorted tetrahedral 2-(amido-prop-2-yl)-6-(1-naphthyl)pyridine aluminum dimethyl complexes, [2-{CMe2N(Ar)}-6-(1-C10H7)C5H3N]AlMe2 [Ar = 2,6-i-Pr2C6H3 (1a), 2,4,6-i-Pr3C6H2 (1b), 4-Br-2,6-i-Pr2C6H2 (1c)], in good yield. The X-ray structures of 1a-1c reveal that complexation has resulted in concomitant C-C bond formation via methyl migration from aluminum to the corresponding imino carbon in L1aryl; in solution, the restricted rotation of the pendant naphthyl group in 1 confers inequivalent methyl ligand environments. The ring opening polymerization of ε-caprolactone employing 1, in the presence of benzyl alcohol, proceeded efficiently at 30 °C producing polymers of narrow molecular weight distribution with the catalytic activities dependent on the nature of the substituent located at the > 1c); at 50 °C 1b mediates 100% conversion of the monomer to polycaprolactone (poly(CL)) in one hour. In addition to 1a, 1b and 1c, the single crystal X-ray structures are reported for L1dipp and L1tripp.

The dynamics of long term phase separation in binary liquid mixtures remains a subject of fundamental interest. Here, we study a binary liquid mixture, where the minority phase is confined...