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Acknowledgements: Thanks are due to Dr Ian Williams, Dr Richard Sear and Prof. Joe Keddie for their helpful comments during the preparation of his paper. The provision of the latex by Synthomer Sdn. Bhd. (Malaysia) and the zinc oxide dispersion by Aquaspersions Ltd (UK) is gratefully acknowledged., Coagulant dipping, the process used in thin glove manufacture, involves electrolyte ions diffusing from the surface of a hand-shaped former into latex compound, causing a deposit (wet gel) to accumulate on the former. In this work, two aspects of the process were examined, both experimentally and theoretically. For the experimental work, a commercial nitrile latex was used. The motion of formers through a latex dipping tank is intuitively expected to affect the electrolyte diffusion and hence the wet gel growth. This was investigated at laboratory scale with small glass formers moving in a metre-long dip tank. Former velocities ranged from zero to almost 0.2 m s-1. No effect of former lateral movement on wet gel thickness was observed. One obvious explanation is that most of the coagulant diffusion occurs within the wet gel deposit, which provides protection to the diffusive flux. However, the critical zone is just ahead of the coagulating front, where coagulant is present in the liquid compound at concentrations below the level needed for coagulation. A fluid mechanical model was constructed that assumed a uniform fluid flow along the side face of a rectangular former. The model confirmed that for calcium nitrate, the most commonly used coagulant, the effect of movement is very small. In the second investigation, coagulant leakage into the host latex compound during the dwell time was investigated by taking samples during repeat static dips. This experiment was modelled using diffusion theory, focusing on the critical zone just outside the wet gel at the point of former withdrawal. The model and experiment agreed well, both showing a small but definite coagulant leakage that tended towards a plateau concentration. Coagulant leakage from a moving former was also considered, from a theoretical perspective. In this case, the mechanism is advective movement of coagulant from the critical zone into the host compound. In the worst case, where all of this coagulant is swept away, the model suggested that the plateau coagulant concentration could reach an amount that would cause coagulation. Reduced flow in the critical zone (boundary layer) and former shape are factors that would reduce leakage.

The solvation shell is essential for the folding and function of proteins, but how it contributes to protein misfolding and aggregation has still to be elucidated. We show that the mobility of solvation shell H2O molecules influences the aggregation rate of the amyloid protein alpha-synuclein (alpha Syn), a protein associated with Parkinson's disease. When the mobility of H2O within the solvation shell is reduced by the presence of NaCl, alpha Syn aggregation rate increases. Conversely, in the presence CsI the mobility of the solvation shell is increased and alpha Syn aggregation is reduced. Changing the solvent from H2O to D2O leads to increased aggregation rates, indicating a solvent driven effect. We show the increased aggregation rate is not directly due to a change in the structural conformations of alpha Syn, it is also influenced by a reduction in both the H2O mobility and alpha Syn mobility. We propose that reduced mobility of alpha Syn contributes to increased aggregation by promoting intermolecular interactions.

Colloidosomes, also known as Pickering emulsion capsules, have attracted attention for encapsulation of hydrophilic and hydrophobic actives. However, current preparation methods are limited to single core structures and require the use of modified/engineered nanoparticles for forming the shell. Here, we report a fast, simple, and versatile method for producing multi-oil core silica colloidosomes via salt-driven assembly of purely hydrophilic commercial nanoparticles dispersed within an Oil-In-Water-In-Oil (O/W/O) double emulsion template. The internal structure and overall diameter of the capsules can be adjusted by altering the primary and secondary emulsification conditions. With this approach, 7 to 35 µm diameter multicore colloidosomes containing 0.9 to 4.2 µm large oil cores were produced. The capsules can easily be functionalized depending on the type of nanoparticles used in the preparation process. Here, metal oxide nanoparticles, such as Fe3O4, TiO2 and ZnO, were successfully incorporated within the structure, conferring specific functional properties (i.e. magnetism, photocatalysis) to the final microcapsules. These capsules can also be ruptured using ultrasound, enabling easy access to the internal core environments. Therefore, we believe this work offers a promising approach for producing multicore colloidosomes with adjustable structure and functionalities for the encapsulation of hydrophobic actives.

Spontaneous formation of vesicles from the self-assembly of two specific surfactants, one zwitterionic (oleyl amidopropyl betaine, OAPB) and the other anionic (Aerosol-OT, AOT), is explored in water using small-angle scattering techniques. Two factors were found to be critical in the formation of vesicles: surfactant ratio, as AOT concentrations less than equimolar with OAPB result in cylindrical micelles or mixtures of micellar structures, and salt concentration, whereby increasing the amount of NaCl promotes vesicle formation by reducing headgroup repulsions. Small-angle neutron scattering measurements reveal that the vesicles are approximately 30-40 nm in diameter, depending on sample composition. Small-angle X-ray scattering measurements suggest preferential partitioning of OAPB molecules on the vesicle inner layer to support vesicular packing. Heating the vesicles to physiological temperature (37 °C) causes them to collapse into smaller ellipsoidal micelles (2-3 nm), with higher salt concentrations (≥10 mM) inhibiting this transition. These aggregates could serve as responsive carriers for loading or unloading of aqueous cargoes such as drugs and pharmaceuticals, with temperature changes serving as a simple release/uptake mechanism.

We report on the preparation of colloidosomes formed with a poly(methyl methacrylate-co-butyl acrylate) latex shell, sealed using calcium alginate as a novel nontoxic and biodegradable sealing agent. The aim is to encapsulate enzymes in detergent formulations. The proposed method, with vegetable oil as the continuous phase, avoids the use of harmful organic solvents. Allura Red has been used as a water-soluble dye, in the core, to analyze the influence of variables such as sodium alginate and latex concentrations on the sealing and release profiles. After formation, the capsules were dispersed in either water or propylene glycol. The capsules have been examined using optical, confocal, and scanning electron microscopies. Working with the highest sodium alginate concentration and latex volume, the encapsulation efficiency is between 60 and 80%. Propylene glycol enables a better dispersion of the capsules compared with water. Dye release data have been fitted to exponential and Michaelis-Menten-type equations, leading to kinetic parameters that allow the simulation of the release process.

Funder: Australian Government Research Training Program (RTP) Scholarship., Funder: Haemokinesis, Patterns in dried droplets are commonly observed as rings left after spills of dirty water or coffee have evaporated. Patterns are also seen in dried blood droplets and the patterns have been shown to differ from patients afflicted with different medical conditions. This has been proposed as the basis for a new generation of low-cost blood diagnostics. Before these diagnostics can be widely used, the underlying mechanisms leading to pattern formation in these systems must be understood. We analyse the height profile and appearance of dispersions prepared with red blood cells (RBCs) from healthy donors. The red cell concentrations and diluent were varied and compared with simple polystyrene particle systems to identify the dominant mechanistic variables. Typically, a high concentration of non-volatile components suppresses ring formation. However, RBC suspensions display a greater volume of edge deposition when the red cell concentration is higher. This discrepancy is caused by the consolidation front halting during drying for most blood suspensions. This prevents the standard horizontal drying mechanism and leads to two clearly defined regions in final crack patterns and height profile. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

Small drug molecules are widely developed and used in the pharmaceutical industry. In the past few years, loading and delivering such molecules using polymer-shell colloidosomes has attracted interest. Traditional polymer capsules fail to encapsulate low-molecular-weight materials for long times, since they are inherently porous and permeable for small molecules. In this paper, we report a method for encapsulating an anticancer drug with small molecule weight, for cell viability tests. The silver-coated colloidosomes are prepared by making an aqueous core capsule with a polymer shell and then adding AgNO3, surfactant, and l-ascorbic acid to form a second shell. The capsules are impermeable and can be triggered using ultrasound. We propose to use the capsules as drug carriers. The silver demonstrates a low cytotoxicity for up to 10 capsules per cell. After the silver shells are triggered by ultrasound, the released doxorubicin, the broken silver fragments, and the doxorubicin loading on the capsule surface all kill cells. The results demonstrate a nonpermeable silver-shell microcapsule with ultrasound sensitivity for potential medical applications.

As all readers of this journal are aware, drug carriers are vital for safe and efficient delivery of therapeutics. Different materials, such as liposomes, metal-organic frameworks, silica particles, micelles and microcapsules can be used as drug delivery carriers. These drug delivery carriers are used to treat various diseases, such as cancers, fungal infections and muscle degeneration.