Continuous production of hydroxyapatite Pickering emulsions using a mesostructured reactor

Lignin from aldehyde-assisted fractionation can provide light-colored Pickering emulsions through colloidal particles formed using alkaline antisolvent

Colloidal lignin particles (CLPs) are gaining attention as eco-friendly stabilizers for Pickering emulsions. Still, conventional lignin sources, like kraft lignin, are often limited by their dark color and strong odor. This study explores, for the first time, the use of a light-colored lignin derived from an aldehyde-assisted fractionation with glyoxylic acid (GA-lignin) for producing CLPs and derived Pickering emulsions. CLPs were produced by antisolvent precipitation with water (CLPs-W, pH 6) and alkaline buffer (CLPs-B, pH 8) as the antisolvents. The results revealed that the selected antisolvent significantly influenced the CLPs' properties. CLPs-W were larger, uniform in size, and hydrophobic, whereas CLPs-B were smaller, agglomerated into clusters, and exhibited greater hydrophilicity. Despite both CLPs' effectiveness in stabilizing oil-in-water emulsions, the stabilization mechanisms differed markedly; CLPs-W formed a robust membrane barrier at the oil-water interface, while CLPs-B facilitated oil droplet bridging. Overall, this work demonstrates that GA-lignin's light color nature offers advantages for Pickering emulsions design, surpassing a lignin typical limitation. This advancement highlights the versatility of GA-lignin-derived CLPs and supports the development of sustainable lignin-based products with significant commercial prospects.

Transitioning from Pickering emulsions to Pickering emulsion hydrogels: A potential advancement in cosmeceuticals

Cosmeceuticals, focusing on enhancing skin health and appearance, heavily rely on emulsions as one of the common mediums. These emulsions pose a challenge due to their dependence on surfactants which are essential for stability but are causing concerns about environmental impact as well as evolving consumer preferences. This has led to research focused on Pickering emulsions (PEs), which are colloidal particle-based emulsion alternatives. Compared to conventional emulsions, PEs offer enhanced stability and functionality in addition to serving as a sustainable alternative but still pose challenges such as rheological control and requiring further improvement in long-term stability, whereby the limitations could be addressed through the introduction of a hydrogel network. In this review, we first highlight the strategies and considerations to optimize active ingredient (AI) absorption and penetration in a PE-based formulation. We then delve into a comprehensive overview of the potential of Pickering-based cosmeceutical emulsions including their attractive features, the various Pickering particles that can be employed, past studies and their limitations. Further, PE hydrogels (PEHs), which combines the features between PE and hydrogel as an innovative solution to address challenges posed by both conventional emulsions and PEs in the cosmeceutical industry is explored. Moreover, concerns related to toxicity and biocompatibility are critically examined, alongside considerations of scalability and commercial viability, providing a forward-looking perspective on potential future research directions centered on the application of PEHs in the cosmeceutical field.

Synthesis of HAp by Means of Sonoprecipitation Method

Biomaterials, like hydroxyapatite (HAp), are the subject of many scientific investigations. Their specific application, however, is determined by the form and some characteristic features of the resulting material. Synthesis methods and optimization procedures leading to a product of predetermined characteristics are therefore of great interest. To broaden the existing knowledge, sonoprecipitation was investigated as a potential method for the production of nanosized HAp particles. The research was carried out in a static mixer (STM) immersed in the ultrasonic bath. The influence of operating conditions, e.g., ultrasonic power PUS (εUS), ultrasonic frequency (fUS), and unit mixing power (εmix), was investigated in terms of nucleation intensity, product quality, and characteristics (particle size distribution (PSD), mean size, shape, etc.). As a result, the optimal conditions for the HAp nanoparticles synthesis (mean size: d~150 nm; length: L1~250 nm; width: L2~80 nm) in the form of needles/whiskers/rods-similar to the shape of the HAp present in natural human bones, free from agglomerates, with negligible signs of particle destruction-were determined. The formation of HAp of smaller sizes (d ≤ 100 nm) and more compact shapes (L1~155 nm, L2~90 nm), useful in bone regeneration processes, was also discussed.

Pickering Emulsions Based in Inorganic Solid Particles: From Product Development to Food Applications

Pickering emulsions (PEs) have attracted attention in different fields, such as food, pharmaceuticals and cosmetics, mainly due to their good physical stability. PEs are a promising strategy to develop functional products since the particles’ oil and water phases can act as carriers of active compounds, providing multiple combinations potentiating synergistic effects. Moreover, they can answer the sustainable and green chemistry issues arising from using conventional emulsifier-based systems. In this context, this review focuses on the applicability of safe inorganic solid particles as emulsion stabilisers, discussing the main stabilisation mechanisms of oil–water interfaces. In particular, it provides evidence for hydroxyapatite (HAp) particles as Pickering stabilisers, discussing the latest advances. The main technologies used to produce PEs are also presented. From an industrial perspective, an effort was made to list new productive technologies at the laboratory scale and discuss their feasibility for scale-up. Finally, the advantages and potential applications of PEs in the food industry are also described. Overall, this review gathers recent developments in the formulation, production and properties of food-grade PEs based on safe inorganic solid particles.

Mixing in the NETmix Reactor

NETmix is a static mixing reactor composed of a network of mixing chambers interconnected by channels. The repetitive mixing pattern inside the reactor enables the use of reduced geometries to represent the NETmix network, such as the ExtendedNUB model, used in this work. Mixing in NETmix is based on the impingement of jets, issuing from channels. Inside the chambers, the jets are engulfed by dynamic vortices which can be quantified using Lagrangian techniques. Batch Lagrangian Mixing Simulation (BLMS) is based on successive injections of particles to measure the fraction of the fluids at the outlet of the mixing chambers. The distribution of the outlet fraction of particles indicates that it is possible to have nearly perfect mixing inside the NETmix chambers, depending on the dimensions of the channels and chambers. The NETmix design is here optimized in relation to the chamber diameter to channel width ratio, D/d. Results from BLMS show that best performance in NETmix occurs for 6.65≤D/d≤6.85.