A Practical Guide to Preparation and Applications of Giant Unilamellar Vesicles Formed via Centrifugation of Water-in-Oil Emulsion Droplets

A molecular strategy for creating functional vesicles with balancing structural stability and stimuli-responsiveness

Vesicles, closed bilayer structures composed of amphiphiles, have attracted considerable attention as functional materials. Structural stability and stimulus responsiveness are required for next-generation functional vesicles. However, there is a dilemma between these properties because the desired membrane structure varies in terms of structural stability and stimulus sensitivity. Herein, we propose a new approach for the development of giant vesicles (GVs) through the molecular design and synthesis of amphiphiles with or without amide linkages, forming hydrogen bonding. From the 1H NMR analysis and fluorescence spectra of environment-responsive probes, intermolecular hydrogen bonding between the amide linkages in the membrane contributed to the enhanced structural stability of the GVs. Moreover, by adding amphiphiles containing a photoresponsive azobenzene moiety to GVs composed of amphiphiles with or without amide linkages, a distinct mechanism of photoresponsive deformation was observed: the former exhibited large and irreversible deformation, while the latter showed a modest and reversible manner due to the photoisomerisation of azobenzene under ultraviolet and subsequent visible light illumination. This difference was also attributed to the membrane structure affected by intermolecular hydrogen bonding. Based on these results, the finding provides a molecular methodology for developing highly functional vesicles.

Internal State of Vesicles Affects Higher Order State of Vesicle Assembly and Interaction

Dynamic soft matter systems composed of functionalized vesicles and liposomes are typically produced and then manipulated through external means, including the addition of exogenous molecules. In biology, natural cells possess greater autonomy, as their internal states are continuously updated, enabling them to effect higher order properties of the system. Therefore, a conceptual and technical gap exists between the natural and artificial systems. We engineered functionalized vesicles to form multicore aggregates capable of self-assembly due to the presence of complementary ssDNA strands. A dynamic process was then triggered through an exogenously triggered on-demand release of an endogenously produced displacer molecule, resulting in multicore aggregate disassembly. This approach explores how internal states of vesicles can affect the external organization, demonstrating a very simple programmable strategy for assembly and then endogenous disassembly. This framework supports the exploration of larger and more complex multicore entities, opening a path toward community behavior and a higher degree of autonomy.

Emerging Designs and Applications for Biomembrane Biosensors

Nature has inspired the development of biomimetic membrane sensors in which the functionalities of biological molecules, such as proteins and lipids, are harnessed for sensing applications. This review provides an overview of the recent developments for biomembrane sensors compatible with either bulk or planar sensing applications, namely using lipid vesicles or supported lipid bilayers, respectively. We first describe the individual components required for these sensing platforms and the design principles that are considered when constructing them, and we segue into recent applications being implemented across multiple fields. Our goal for this review is to illustrate the versatility of nature's biomembrane toolbox and simultaneously highlight how biosensor platforms can be enhanced by harnessing it.

Development of cream bases suitable for personalized cosmetic products

Background and aims

The individualization of cosmetic products or personalized dermatology preparations are in great demand at the present time.

Methods

24 emulsifying cream bases were proposed which were prepared by the classical, automatic and semi-automatic methods, respectively, and the physical stability resulted from the three types of homogenization was taken into account. Texture parameters were also studied for the most stable cream bases in the preformulation stage and the t - statistical test was applied. In order to choose the most optimal preservative, the effectiveness of the NipaEster solution 0.1%, Cosgard and Euxyl® PE 9010 was tested on the strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans.

Results

9 cream bases were stable through all the preparation methods used, and preservation was achieved with Euxyl® PE 9010. Following the texture parameters, significant differences were observed for the same formula in the case of choosing a different preparation method.

Conclusions

Formulas F1, with methyl glucose sesquistearate as emulsifier, F8, with cetearyl glucosite as emulsifier, and F14, with Ceteareth-20 can be used as cream bases for customized products.

Synthetic control of actin polymerization and symmetry breaking in active protocells

Nonlinear biomolecular interactions on membranes drive membrane remodeling crucial for biological processes including chemotaxis, cytokinesis, and endocytosis. The complexity of biomolecular interactions, their redundancy, and the importance of spatiotemporal context in membrane organization impede understanding of the physical principles governing membrane mechanics. Developing a minimal in vitro system that mimics molecular signaling and membrane remodeling while maintaining physiological fidelity poses a major challenge. Inspired by chemotaxis, we reconstructed chemically regulated actin polymerization inside vesicles, guiding membrane self-organization. An external, undirected chemical input induced directed actin polymerization and membrane deformation uncorrelated with upstream biochemical cues, suggesting symmetry breaking. A biophysical model incorporating actin dynamics and membrane mechanics proposes that uneven actin distributions cause nonlinear membrane deformations, consistent with experimental findings. This protocellular system illuminates the interplay between actin dynamics and membrane shape during symmetry breaking, offering insights into chemotaxis and other cell biological processes.

Microrail-assisted liposome trapping and aligning in microfluidic channels

Liposome assemblies with a specific shape are potential cell tissue models for studying intercellular communication. Microfluidic channels that can trap liposomes have been constructed to achieve efficient and high-throughput manipulation and observation of liposomes. However, the trapping and alignment of multiple liposomes in a specific space are still challenging because the liposomes are soft and easily ruptured. In this study, we focused on a microrail-assisted technique for manipulating water-in-oil (w/o) emulsions. In this technique, w/o emulsions are trapped under the microrails through a surface energy gradient. First, we investigated whether the microrail channel can be applied for liposome trapping and alignment and found that the numerical simulations showed that drag forces in the direction of the microrail acted on the liposomes, thereby moving the liposomes from the main channel to the microrail. Next, we designed a microrail device based on the simulation results and trapped liposomes using the device. Resultantly, 24.7 ± 8.5 liposomes were aligned under the microrail within an hour, and the microrail was filled with liposomes for 3 hours. Finally, we prepared the microrail devices with y-shaped and ring-shaped microrails and demonstrated the construction of liposome assemblies with specific shapes, not only the straight shape. Our results indicate that the microrail-assisted technique is a valuable method for manipulating liposomes because it has the potential to provide various-shaped liposome assemblies. We believe the microrail channel will be a powerful tool for constructing liposome-based cell-cell interaction models.

Lipid vesicle-based molecular robots

A molecular robot, which is a system comprised of one or more molecular machines and computers, can execute sophisticated tasks in many fields that span from nanomedicine to green nanotechnology. The core parts of molecular robots are fairly consistent from system to system and always include (i) a body to encapsulate molecular machines, (ii) sensors to capture signals, (iii) computers to make decisions, and (iv) actuators to perform tasks. This review aims to provide an overview of approaches and considerations to develop molecular robots. We first introduce the basic technologies required for constructing the core parts of molecular robots, describe the recent progress towards achieving higher functionality, and subsequently discuss the current challenges and outlook. We also highlight the applications of molecular robots in sensing biomarkers, signal communications with living cells, and conversion of energy. Although molecular robots are still in their infancy, they will unquestionably initiate massive change in biomedical and environmental technology in the not too distant future.

Synthetic Cells Revisited: Artificial Cells Construction Using Polymeric Building Blocks

The exponential growth of research on artificial cells and organelles underscores their potential as tools to advance the understanding of fundamental biological processes. The bottom-up construction from a variety of building blocks at the micro- and nanoscale, in combination with biomolecules is key to developing artificial cells. In this review, artificial cells are focused upon based on compartments where polymers are the main constituent of the assembly. Polymers are of particular interest due to their incredible chemical variety and the advantage of tuning the properties and functionality of their assemblies. First, the architectures of micro- and nanoscale polymer assemblies are introduced and then their usage as building blocks is elaborated upon. Different membrane-bound and membrane-less compartments and supramolecular structures and how they combine into advanced synthetic cells are presented. Then, the functional aspects are explored, addressing how artificial organelles in giant compartments mimic cellular processes. Finally, how artificial cells communicate with their surrounding and each other such as to adapt to an ever-changing environment and achieve collective behavior as a steppingstone toward artificial tissues, is taken a look at. Engineering artificial cells with highly controllable and programmable features open new avenues for the development of sophisticated multifunctional systems.

Synthetic control of actin polymerization and symmetry breaking in active protocells

Non-linear biomolecular interactions on the membranes drive membrane remodeling that underlies fundamental biological processes including chemotaxis, cytokinesis, and endocytosis. The multitude of biomolecules, the redundancy in their interactions, and the importance of spatiotemporal context in membrane organization hampers understanding the physical principles governing membrane mechanics. A minimal, in vitro system that models the functional interactions between molecular signaling and membrane remodeling, while remaining faithful to cellular physiology and geometry is powerful yet remains unachieved. Here, inspired by the biophysical processes underpinning chemotaxis, we reconstituted externally-controlled actin polymerization inside giant unilamellar vesicles, guiding self-organization on the membrane. We show that applying undirected external chemical inputs to this system results in directed actin polymerization and membrane deformation that are uncorrelated with upstream biochemical cues, indicating symmetry breaking. A biophysical model of the dynamics and mechanics of both actin polymerization and membrane shape suggests that inhomogeneous distributions of actin generate membrane shape deformations in a non-linear fashion, a prediction consistent with experimental measurements and subsequent local perturbations. The active protocellular system demonstrates the interplay between actin dynamics and membrane shape in a symmetry breaking context that is relevant to chemotaxis and a suite of other biological processes.

Lipid-Based Nanocarriers for Delivery of Neuroprotective Kynurenic Acid: Preparation, Characterization, and BBB Transport

Encapsulation possibilities of an extensively investigated neuroprotective drug (kynurenic acid, KYNA) are studied via lipid-based nanocarriers to increase the blood-brain barrier (BBB) specific permeability. The outcomes of various preparation conditions such as stirring and sonication time, concentration of the lipid carriers and the drug, and the drug-to-lipid ratio are examined. Considering the experimentally determined encapsulation efficiency, hydrodynamic diameter, and ζ-potential values, the initial lipid and drug concentration as well as the stirring and sonication time of the preparation were optimized. The average hydrodynamic diameter of the prepared asolectin-(LIP) and water-soluble lipopolymer (WSLP)-based liposomes was found to be ca. 25 and 60 nm under physiological conditions. The physicochemical characterization of the colloidal carriers proves that the preparation of the drug-loaded liposomes was a successful process, and secondary interactions were indicated between the drug molecule and the polymer residues around the WSLP membrane. Dissolution profiles of the active molecule under physiological conditions were registered, and the release of the unformulated and encapsulated drug is very similar. In addition to this outcome, the in vitro polar brain lipid extract (porcine)-based permeability test proved the achievement of two- or fourfold higher BBB specific penetration and lipid membrane retention for KYNA in the liposomal carriers relative to the unformatted drug.