Current Opinion in Colloid & Interface Science最新文献

In surfactant solutions, the bulk hydrodynamic flow couples to extensional/compressional surface flows due to Marangoni stresses induced at the interface. With the increasing surfactant concentration, these Marangoni stresses can suppress the surface flows and lead to non-moving, retarded, surfaces. We review this phenomenon with special focus on the dynamic dewetting of a substrate pulled out of a pool of surfactant solution. In this case, the dewetting meniscus surface can be retarded (fully or partially) because of the appearance of surface tension gradients opposing the flow in the adjacent liquid. With an increasing flow velocity, the non-uniformity of the meniscus surface becomes stronger resulting in its separation on a mobile and an immobile part with a sharp transition between them. The presence of a non-uniform adsorption layer at the meniscus surface strongly complicates the dewetting dynamics which becomes dependent on the surfactant balance at the surface.

Lyotropic non-lamellar liquid crystalline (LLC) nano-self-assemblies (including cubosomes and hexosomes) are attractive versatile platforms for the encapsulation and delivery of drugs and nutritional molecules. This is due to their unique structural features and architectural arrangements that afford loading of small molecules and macromolecules having different physicochemical properties with high efficiency. Considering the reported health-promoting effects of long-chain omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and their precursors ω-3 PUFA monoacylglycerols; here, we focus on physicochemical and biological properties of a new family of non-lamellar LLC nanoparticles assembled either from binary mixtures of phosphatidylglycerol and three types of ω-3 PUFAs, or from single ω-3 PUFA monoacylglycerols. We discuss recent progress in understanding their complexity, pH sensitivity, and structural tunability, as well as highlight their potential applications in health and medicine.

Wetting plays a crucial role in achieving efficient condensation in applications such as atmospheric water harvesting, air conditioning and refrigeration, and thermal power plants. Despite decades of research, the industrial implementation of dropwise condensation, which is often superior to filmwise condensation, has been limited, mostly due to the poor durability of promoter coatings and the challenge of achieving dropwise condensation for non-aqueous working fluids. Both areas have seen noteworthy advancements over the past few years, some of which we highlight in this review article. For example, recognizing that contact angle hysteresis, not contact angles per se, are responsible for enabling dropwise condensation, ultra-smooth liquid-like polymer coatings and lubricant-infused surfaces were developed for use with water and non-aqueous working fluids. There are also several new developments for passive and active droplet removal. Advances in coating durability include a better understanding in the failure mechanisms and physics-informed designs of new coating processes and chemistries.

Wetting of solid surfaces by liquid deposition, contact dispensing, drop transfer, collision of wet particles, or during coating processes is often accompanied by the formation of liquid bridges between two or more solid substrates. They appear in many applications, like material science, microfluidics, biomedical, chemical, or aerospace engineering, and different fields of physics. In this study, the flows accompanying lifting of a Hele-Shaw cell, stretching or shearing of a liquid bridge, as well as liquid bridge flows observed during printing processes and other important applications, are briefly reviewed. Such flows are governed by surface tension, inertia, stresses associated with the liquid rheology, and forces caused by the substrate's wettability. Instabilities of liquid bridges lead to the formation of finger-like structures on the substrate or the appearance of cavities at the wetted region of the wall. The time required for jet pinch-off also determines the residual liquid volume on both solid bodies.

In recent years, a growing understanding of the underlying mechanisms of autoinflammatory and autoimmune disease has enabled significant advances in biomaterial therapeutics for their treatment and prevention. Drug-free or immune-active polymeric materials are of particular interest due to their chemical tunability, multifaceted mechanisms of action, and potential to offer alternatives to conventional treatments. While in many cases the relationships between polymer physicochemical properties and the immune processes they influence are context-dependent and require further clarity, several concepts are emerging that can be applied in the design of anti-inflammatory materials. This review highlights recent work that investigates these relationships, as well as work that applies them to immunomodulatory biomaterials for the treatment or prevention of autoimmune and autoinflammatory diseases.

Protein nanocages used as emulsion stabilizing colloidal particles are opening possibilities to the design of novel delivery systems for food, pharmaceutical and cosmetic applications. Protein nanocage-stabilized emulsions are able to co-deliver hydrophilic and hydrophobic compounds. The surface chemistry of the particles is one of the factors that determines their ability to stabilize the emulsion. Hence, the importance in developing strategies to rationally tailor the nanocage surface chemistry. This contribution summarizes recent advances in protein nanocage Pickering emulsions and the methods used to modify the nanocages. It discusses future strategies that may allow the modification of protein nanocages based on current knowledge of Pickering emulsions and protein nanocage engineering technology. The characterization methods for the investigation of these protein nanocages and nanocage stabilized emulsions are described. Finally, the applications of protein nanocages for nutrient delivery in the gastrointestinal tract will be discussed. This contribution provides a perspective for future work on protein nanocage stabilized emulsions.

Natural pigments provide a range of appealing colors to flowers, fruits, and vegetables while exhibiting potential beneficial health effects. In contrast, synthetic food colorants are often suggested to be associated with adverse health effects yet are known to have relatively high color stability during processing and storage. Unlike artificial colorants, natural pigments are somewhat unstable and susceptible to chemical and enzymatic degradation, leading to enhanced color loss. Therefore, their use as pigments is constrained, and stabilization by hydrocolloids is being explored. In addition to the texturizing properties of hydrocolloids, they can interact with natural pigments, affecting their stability. Therefore, hydrocolloids can improve the chemical and physical stability of pigments, resulting in enhanced color stability. This review summarizes up-to-date information regarding the stabilization of natural pigments such as anthocyanins, betalains, carotenes, C-phycocyanins, and chlorophylls, using hydrocolloids, in relation to the hydrocolloid properties, pigment structure, and stabilization methods and mechanisms.

The term biosurfactants refers to a complex mixture of metabolites with surface-active properties produced by specific microorganisms. However, nowadays trends moves towards isolation, screening and purifying single biocompatible, biodegradable biosurfactants with high commercialisation potential. Current legislation limiting petrochemicals combined with environmentally concerned consumers did not only stimulate research and development but it also promoted large-scale production of this class of molecules. However, recent data recorded on single congeners question the actual pertinence of using the word ‘biosurfactant’ associated to these molecules. By evaluating the accepted characteristics of surfactants and comparing them to the actual self-assembly and bulk properties in water of molecules traditionally called ‘biosurfactants’, this opinion article aims at showing that the term ‘biosurfactant’ can be somewhat reductive when applied to specific individual compounds produced by fermentation. The use of a more generic term, like bioamphiphile could probably be more pertinent and appropriate for consideration in the future.

Peptide self-assemblies display distinct physical and structural transitions, ranging from the early small assemblies, or oligomers, to long nanosheets, nanobelts, nanotubes, and nanofibers formed into distinct hydrogels. Because of changes in charge distribution and protection of cleavage sites, self-assembled peptides can have high resistance to enzymatic degradation. As potential candidates for biomedical applications, it is important to understand how peptides self-assemble and how the processes can be manipulated. Following the diverse approaches recently reported to control their assembling processes, many de novo-designed short peptides can be applied to infection control in various conditions, such as nanocarriers in drug delivery, wound dressings, and postsurgery antimicrobial/antiviral spreads and coatings. Here we present an overview of recent advances in peptide self-assembly mechanisms and the relationship between self-assembly behaviors and their infection-combatting effects. At the end of this review, concluding remarks and future perspectives are provided.

Over the past decade, there has been a growing interest in the study of multicomponent drops. These drops exhibit unique phenomena, as the interplay between hydrodynamics and the evolving physicochemical properties of the mixture gives rise to distinct and often unregulated behaviors. Of particular interest is the complex dynamic behavior of the drop contact line, which can display self-lubrication effect. The presence of a slipping contact line in self-lubricating multicomponent drops can suppress the coffee-stain effect, conferring valuable technological applications. This review will explain the current understanding of the self-lubrication effect of drops, and cover an analysis of fundamental concepts and recent advances in colloidal assembly. The potential applications of self-lubricating drops across different fields will also be highlighted.