Direction-Specific Release from Capsules with Homogeneous or Janus Shells Using an Ultrasound Approach

Emulsion-Based Delivery Systems to Enhance the Functionality of Bioactive Compounds: Towards the Use of Ingredients from Natural, Sustainable Sources

In recent years, the trend in the population towards consuming more natural and sustainable foods has increased significantly. This claim has led to the search for new sources of bioactive compounds and extraction methods that have less impact on the environment. Moreover, the formulation of systems to protect these compounds is also focusing on the use of ingredients of natural origin. This article reviews novel, natural alternative sources of bioactive compounds with a positive impact on sustainability. In addition, it also contains information on the most recent studies based on the use of natural (especially from plants) emulsifiers in the design of emulsion-based delivery systems to protect bioactive compounds. The properties of these natural-based emulsion-delivery systems, as well as their functionality, including in vitro and in vivo studies, are also discussed. This review provides relevant information on the latest advances in the development of emulsion delivery systems based on ingredients from sustainable natural sources.

Interfacial Imide Polymerization of Functionalized Filled Microcapsule Templates by the Pickering Emulsion Method for the Rapid Removal of 3,4,5-Trichlorophenol from Wastewater

In this work, an olive oil-filled composite capsule (C-O/W) adsorbent was prepared for the adsorption of 3,4,5-trichlorophenol (3,4,5-TCP) by the emulsion templating method. Using methylene diisocyanate (HDI) and 1,6-hexanediamine (HMDA) as functional monomers, olive oil was encapsulated in a shell layer composed of graphene oxide and a polymer by interfacial imine polymerization. The contaminant target was efficiently removed by the hydrophobic interaction between olive oil and chlorophenols. The removal of 3,4,5-TCP was remarkable, with an encapsulation rate of 85%. The unique microcapsule structure further enhanced the kinetic performance, which reached 92% of the maximum value within 40 min. The adsorption of different chlorophenols was investigated using 2-chlorophenol (2-CP), 2,6-dichlorophenol (2,6-DCP), and 3,4,5-TCP. The adsorption of 3,4,5-TCP by the C-O/W microcapsules was found to be much higher than that of other chlorophenols. When analyzing a real sample, the content of 3,4,5-TCP was significantly reduced after adsorption by the C-O/W microcapsules, demonstrating that the C-O/W microcapsules were also capable of removing 3,4,5-TCP from a complex environment. This simple and inexpensive preparation strategy provides a new method for the synthesis of functionalized C-O/W microcapsule adsorbents and an effective adsorbent of 3,4,5-TCP.

Next-Generation Colloidal Materials for Ultrasound Imaging Applications

Ultrasound has important applications, predominantly in the field of diagnostic imaging. Presently, colloidal systems such as microbubbles, phase-change emulsion droplets and particle systems with acoustic properties and multiresponsiveness are being developed to address typical issues faced when using commercial ultrasound contrast agents, and to extend the utility of such systems to targeted drug delivery and multimodal imaging. Current technologies and increasing research data on the chemistry, physics and materials science of new colloidal systems are also leading to the development of more complex, novel and application-specific colloidal assemblies with ultrasound contrast enhancement and other properties, which could be beneficial for multiple biomedical applications, especially imaging-guided treatments. In this article, we review recent developments in new colloids with applications that use ultrasound contrast enhancement. This work also highlights the emergence of colloidal materials fabricated from or modified with biologically derived and bio-inspired materials, particularly in the form of biopolymers and biomembranes. Challenges, limitations, potential developments and future directions of these next-generation colloidal systems are also presented and discussed.

Electric-field-induced deformation, yielding, and crumpling of jammed particle shells formed on non-spherical Pickering droplets

Droplets covered with densely packed solid particles, often called Pickering droplets, are used in a variety of fundamental studies and practical applications. For many applications, it is essential to understand the mechanics of such particle-laden droplets subjected to external stresses. Several research groups have studied theoretically and experimentally the deformation, relaxation, rotation, and stability of Pickering droplets. Most of the research concerns spherical Pickering droplets. However, little is known about non-spherical Pickering droplets with arrested particle shells subjected to compressive stress. The experimental results presented here contribute to filling this gap in research. We deform arrested non-spherical Pickering droplets by subjecting them to electric fields, and study the effect of droplet geometry and size, as well as particle size and electric field strength, on the deformation and yielding of arrested non-spherical Pickering droplets. We explain why a more aspherical droplet and/or a droplet covered with a shell made of larger particles required higher electric stress to deform and yield. We also show that an armored droplet can absorb the electric stress differently (i.e., through either in-plane or out-of-plane particle rearrangements) depending on the strength of the applied electric field. Furthermore, we demonstrate that particle shells may fail through various crumpling instabilities, including ridge formation, folding, and wrinkling, as well as inward indentation.

Nanoparticles in Polyelectrolyte Multilayer Layer-by-Layer (LbL) Films and Capsules—Key Enabling Components of Hybrid Coatings

Originally regarded as auxiliary additives, nanoparticles have become important constituents of polyelectrolyte multilayers. They represent the key components to enhance mechanical properties, enable activation by laser light or ultrasound, construct anisotropic and multicompartment structures, and facilitate the development of novel sensors and movable particles. Here, we discuss an increasingly important role of inorganic nanoparticles in the layer-by-layer assembly—effectively leading to the construction of the so-called hybrid coatings. The principles of assembly are discussed together with the properties of nanoparticles and layer-by-layer polymeric assembly essential in building hybrid coatings. Applications and emerging trends in development of such novel materials are also identified.

Polymer Capsules with Hydrophobic Liquid Cores as Functional Nanocarriers

Recent developments in the fabrication of core-shell polymer nanocapsules, as well as their current and future applications, are reported here. Special attention is paid to the newly introduced surfactant-free fabrication method of aqueous dispersions of nanocapsules with hydrophobic liquid cores stabilized by amphiphilic copolymers. Various approaches to the efficient stabilization of such vehicles, tailoring their cores and shells for the fabrication of multifunctional, navigable nanocarriers and/or nanoreactors useful in various fields, are discussed. The emphasis is placed on biomedical applications of polymer nanocapsules, including the delivery of poorly soluble active compounds and contrast agents, as well as their use as theranostic platforms. Other methods of fabrication of polymer-based nanocapsules are briefly presented and compared in the context of their biomedical applications.

Size Determination of Polystyrene Sub-Microspheres Using Transmission Spectroscopy

Nano/micro polystyrene (PS) beads have found many applications in different fields spanning from drug delivery, bio-diagnostics, and hybrid plasmonics to advanced photonics. The sizes of the PS beads are an important parameter, especially in plasmonic and photonic experiments. In this work, we demonstrate a quick and straightforward method to estimate the diameters of sub-microspheres (0.2 μm to 0.8 μm) using the transmission spectra of a close-packed monolayer of polystyrene beads on glass or quartz substrates. Experimental transmission spectra of the PS monolayers were verified against finite-difference time-domain (FDTD) simulation and showed good agreement. The effects of the substrates on the transmission spectra and, hence, the accuracy of the method were also studied by simulation, which showed that common transparent substrates only cause minor deviation of the PS bead sizes calculated by the proposed method.