Liposome Deformation Research Articles

Evaluation of the interactions between human stratum corneum and liposome formulations using QCM-D

The interactions between human stratum corneum (SC) and two liposomal formulations, azithromycin (AZM)- and nisin-loaded liposomal formulations designed for topical/intradermal application, were investigated using quartz crystal microbalance with dissipation (QCM-D). SC isolated from cadaver skin was affixed onto the QCM sensor's surface. The liposome formulations were prepared using the thin-film rehydration method. The particle sizes of the blank liposome, nisin-loaded, AZM-loaded, and combined-loaded liposomes were measured as 90.7 ± 0.58 nm, 100.8 ± 2.5 nm, 136.9 ± 6.5 nm, and 174.3 ± 9.8 nm, respectively. The frequency shifts with blank and drug-loaded liposomes were ∼20 and ∼25 Hz, respectively as a result of the formation of bilayers on gold surface in a two-step process, adsorption of intact vesicles followed by the formation of the bilayer upon rinsing with water. The frequency shifts for blank and drug-loaded liposomes on SC were ∼8 and ∼15 Hz, respectively. These results show that the liposomes are deposited as bilayers on SC with both the blank and drug-loaded liposomes. The increase in frequency shifts with drug-loaded liposomes indicate the deposition of drug along with lipids onto both the gold and SC surfaces. More significantly, the data showed much slower kinetics of liposome component spreading onto the SC than on gold. The changes in dissipation that accompanies these differences in frequency shifts show transformation of vesicle onto rigid bilayer on gold upon rinsing with water, but direct formation of lipid bilayers on SC. The findings of this study contribute to a better understanding of the interaction between SC and liposomes, such as adsorption, deformation, and rupture of liposomes on different substrates, paving the way for investigating topical and intradermal mechanisms of drug delivery and cosmetic products developed based on liposome formulations.

Domain-specific deformation of phase-separated liposomes

Domain-specific deformation of phase-separated liposomes

Photoresponsive peptide materials: Spatiotemporal control of self-assembly and biological functions.

Peptides work as both functional molecules to modulate various biological phenomena and self-assembling artificial materials. The introduction of photoresponsive units to peptides allows the spatiotemporal remote control of their structure and function upon light irradiation. This article overviews the photoresponsive peptide design, interaction with biomolecules, and applications in self-assembling materials over the last 30 years. Peptides modified with photochromic (photoisomerizable) molecules, such as azobenzene and spiropyran, reversibly photo-controlled the binding to biomolecules and nanostructure formation through self-assembly. Photocleavable molecular units irreversibly control the functions of peptides through cleavage of the main chain and deprotection by light. Photocrosslinking between peptides or between peptides and other biomolecules enhances the structural stability of peptide assemblies and complexes. These photoresponsive peptides spatiotemporally controlled the formation and dissociation of peptide assemblies, gene expressions, protein-drug interactions, protein-protein interactions, liposome deformation and motility, cytoskeleton structure and stability, and cell functions by appropriate light irradiation. These molecular systems can be applied to photo-control biological functions, molecular robots, artificial cells, and next-generation smart drug delivery materials.

Gas‐Liquid Flow‐Induced Characteristics of Dispersed Liposome‐Based Particles

AbstractLiposomes are closed bilayers of phospholipids formed in aqueous media. The hydrodynamic property of colloidal dispersions of liposomes is one of the factors which alter the structure of liposomes. The present review article discusses the mechanistic aspects of the deformation, breakage, and fusion of liposomes in different liquid shear flows. Then, characteristic features reported with respect to the particles consisting of liposomes and bubbles are discussed to explore the role of shear flows induced by the acoustically active bubbles. Furthermore, the gas‐liquid flow‐induced characteristics of liposomes are described for their application to kinetically controllable enzymatic reactions in bubble‐column bioreactors.

Liposome Deformation Induced by Membrane-Binding Peptides.

This paper presents an investigation of liposome deformation and shape distortion using four membrane-binding peptides: TAT and C105Y as cell-penetrating peptides (CPPs), and melittin and ovispirin as antimicrobial peptides (AMPs). Liposome deformation was monitored utilizing fluorescent microscopy, while the binding of peptides to the DOPC membrane was estimated through capacitance measurements. The degree of liposome deformation and shape distortion was found to be higher for the CPPs compared to the AMPs. Additionally, it was observed that C105Y did not induce liposome rupture, unlike the other three peptides. We propose that these variations in liposome distortion may be attributed to differences in secondary structure, specifically the presence of an α-helix or random coil. Our studies offer insight into the use of peptides to elicit control of liposome architecture and may offer a promising approach for regulating the bodies of liposomal molecular robots.

Computational Study on the Regulatory Mechanism of Cell Membrane Wrapping on Liposomes by Embedded Bowl-like Nanostructures for Drug Delivery

Controlling the nanoparticle’s (NP) ability to facilitate cell uptake is particularly desirable for biomedical applications, such as drug delivery. Despite growing evidence highlighting the pivotal role of mechanical properties in biological performances of NPs, consensus regarding how stiffness regulates the cell entry of NPs is lacking. Here, we design and elucidate cell membrane wrapping on soft liposomes in which rigid bowl-like nanostructures are embedded. Compared with pure liposomes, which are often partially wrapped by a membrane due to the high energy barrier associated with the oblate deformation, embedded nanobowls provide physical support to promote wrapping by increasing the liposome rigidity. Through correlating liposome deformation, invagination, and nanobowl orientation, two distinct pathways of cell membrane wrapping on nanobowl-supported liposomes are identified. Different from alternative methods of tuning the rigidity of NPs uniformly, the nanobowl-supported liposome is characterized by mechanical heterogeneity and nanobowl rotation, which correlates with liposome deformation to promote endocytic wrapping. Once the nanobowl’s rotation is restrained, wrapping turns out to be accomplished via membrane protrusion rather than invagination, and the wrapped liposome could be trapped with frustrated internalization and potential membrane perturbation. Following this principle, moderate decreases of the nanobowl size and adhesive strength with the liposome can facilitate the nanobowl’s rotation to promote cell uptake. These results are expected to improve our ability to develop better NPs for enhanced drug delivery.

Synthetic Membrane Shaper for Controlled Liposome Deformation.

Shape defines the structure and function of cellular membranes. In cell division, the cell membrane deforms into a "dumbbell" shape, while organelles such as the autophagosome exhibit "stomatocyte" shapes. Bottom-up in vitro reconstitution of protein machineries that stabilize or resolve the membrane necks in such deformed liposome structures is of considerable interest to characterize their function. Here we develop a DNA-nanotechnology-based approach that we call the synthetic membrane shaper (SMS), where cholesterol-linked DNA structures attach to the liposome membrane to reproducibly generate high yields of stomatocytes and dumbbells. In silico simulations confirm the shape-stabilizing role of the SMS. We show that the SMS is fully compatible with protein reconstitution by assembling bacterial divisome proteins (DynaminA, FtsZ:ZipA) at the catenoidal neck of these membrane structures. The SMS approach provides a general tool for studying protein binding to complex membrane geometries that will greatly benefit synthetic cell research.

Actuating tension-loaded DNA clamps drives membrane tubulation.

Membrane dynamics in living organisms can arise from proteins adhering to, assembling on, and exerting force on cell membranes. Programmable synthetic materials, such as self-assembled DNA nanostructures, offer the capability to drive membrane-remodeling events that resemble protein-mediated dynamics but with user-defined outcomes. An illustrative example is the tubular deformation of liposomes by DNA nanostructures with purposely designed shapes, surface modifications, and self-assembling properties. However, stimulus-responsive membrane tubulation mediated by DNA reconfiguration remains challenging. Here, we present the triggered formation of membrane tubes in response to specific DNA signals that actuate membrane-bound DNA clamps from an open state to various predefined closed states, releasing prestored energy to activate membrane deformation. We show that the timing and efficiency of vesicle tubulation, as well as the membrane tube widths, are modulated by the conformational change of DNA clamps, marking a solid step toward spatiotemporal control of membrane dynamics in an artificial system.

Recruitment of Irgb6 to the membrane is a direct trigger for membrane deformation.

Irgb6 is a member of interferon γ-induced immunity related GTPase (IRG), and one of twenty “effector” IRGs, which coordinately attack parasitophorous vacuole membrane (PVM), causing death of intracellular pathogen. Although Irgb6 plays a pivotal role as a pioneer in the process of PVM disruption, the direct effect of Irgb6 on membrane remained to be elucidated. Here, we utilized artificial lipid membranes to reconstitute Irgb6-membrane interaction in vitro, and revealed that Irgb6 directly deformed the membranes. Liposomes incubated with recombinant Irgb6 were drastically deformed generating massive tubular protrusions in the absence of guanine nucleotide, or with GMP-PNP. Liposome deformation was abolished by incubating with Irgb6-K275A/R371A, point mutations at membrane targeting residues. The membrane tubules generated by Irgb6 were mostly disappeared by the addition of GTP or GDP, which are caused by detachment of Irgb6 from membrane. Binding of Irgb6 to the membrane, which was reconstituted in vitro using lipid monolayer, was stimulated at GTP-bound state. Irgb6 GTPase activity was stimulated by the presence of liposomes more than eightfold. Irgb6 GTPase activity in the absence of membrane was also slightly stimulated, by lowering ionic strength, or by increasing protein concentration, indicating synergistic stimulation of the GTPase activity. These results suggest that membrane targeting of Irgb6 and resulting membrane deformation does not require GTP, but converting into GTP-bound state is crucial for detaching Irgb6 from the membrane, which might coincident with local membrane disruption.

Molecular Cybernetics: Challenges toward Cellular Chemical Artificial Intelligence

AbstractResearch on so‐called “chemical artificial intelligence” (CAI) is an emerging field with the aim of constructing information‐processing systems with learning capabilities based on chemical methodologies. This can be regarded as an attempt to reconstruct Cybernetics using molecular based systems. Many chemical reaction systems with computational abilities are proposed, but most are fixed functions that deliver molecular output for a given molecular input. On the other hand, chemical AI is a system with learning capability; namely, the output should be variable and gradually change upon repeated molecular inputs. In this paper, a compartmentalization approach for implementing cellular chemical AI using liposomes is discussed. The existing studies in terms of the methods used for assembling systems consisting of many liposomes with different functions, methods for achieving recursiveness and plasticity in chemical reaction systems, and methods for reconfiguring the network topology by liposome deformation are reviewed. Issues that must be addressed in order to realize chemical AI are also identified.

Liposome Deformation Induced by Random Coil and α-Helical Peptides

Liposome Deformation Induced by Random Coil and α-Helical Peptides

FtsZ induces membrane deformations via torsional stress upon GTP hydrolysis

FtsZ is a key component in bacterial cell division, being the primary protein of the presumably contractile Z ring. In vivo and in vitro, it shows two distinctive features that could so far, however, not be mechanistically linked: self-organization into directionally treadmilling vortices on solid supported membranes, and shape deformation of flexible liposomes. In cells, circumferential treadmilling of FtsZ was shown to recruit septum-building enzymes, but an active force production remains elusive. To gain mechanistic understanding of FtsZ dependent membrane deformations and constriction, we design an in vitro assay based on soft lipid tubes pulled from FtsZ decorated giant lipid vesicles (GUVs) by optical tweezers. FtsZ filaments actively transform these tubes into spring-like structures, where GTPase activity promotes spring compression. Operating the optical tweezers in lateral vibration mode and assigning spring constants to FtsZ coated tubes, the directional forces that FtsZ-YFP-mts rings exert upon GTP hydrolysis can be estimated to be in the pN range. They are sufficient to induce membrane budding with constricting necks on both, giant vesicles and E.coli cells devoid of their cell walls. We hypothesize that these forces result from torsional stress in a GTPase activity dependent manner.

Detailed analysis of liposome adsorption and its rupture on the liquid-solid interface monitored by LSPR and QCM-D integrated sensor

Liposomes have been attracted attention, because liposomes can mimic the lipid bilayer membrane of cells. Scientists apply liposomes for drug delivery systems (DDSs) and for artificial cells. Hence, the handling of liposomes is very important. In particular, it is difficult to control the adsorption of the liposome onto the target selectively and the release of the drug by its own rupture. Therefore, scientists are looking for the way to carefully monitor the behavior of liposomes from adsorption to rupture in deep.We integrated quartz crystal microbalance dissipation (QCM–D) and localized surface plasmon resonance (LSPR) into a single sensor and monitored the signals from the sensor on the adsorption and rupture of liposome. The integrated sensor detected resonance frequency and dissipation from QCM-D, and wavelength shifts from LSPR simultaneously. The integrated sensor successfully monitored conformational changes of liposomes in real time upon exposure to the surfactant, Triton X-100. The data clearly revealed liposome adsorption and deformation, and disruption of membrane integrity by normalizing three signals, resonance frequency, resonance resistance and wavelength shift. In fact, we found that normalized signals were divided into 5 steps through the experiment: liposome adsorption, liposome deformation slightly, liposome conjugated with micelles of surfactant, liposome disruption and lipid bilayer covered on the surface. These results indicate that our device provides a powerful tool to gain deeper insights into biomolecular interactions, expanding numerous applications such as monitoring of conformational changes in proteins, oligonucleotides, viruses, bacteria, vesicles, and cells.

Liposome Fusion Mediated by Hydrophobic Magnetic Nanoparticles Stabilized with Oleic Acid and Modulated by an External Magnetic Field.

Membrane fusion is considered relevant in countless scientific areas and biotechnological processes, ranging from vital life events to biomedicine, pharmaceuticals, and materials engineering, among others. In this study, we employed hydrophobic oleic acid (OA)-coated magnetite (Fe3O4) nanoparticles (MNP-OA) as a platform to induce the fusion of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine liposomes [large unilamellar vesicles (LUVs)] in a colloidal dispersion. This fusion was monitored through dynamic light scattering, turbidimetry, and fluorescence assay using the well-known Tb/dipicolinic acid (DPA) complex formation assay. MNP-OA have shown to be able to induce fusion with the mixing of liposomal inner content with direct dependence on the nanoparticle concentration added to the LUVs. Moreover, changes in the permeability of the liposome bilayer, upon the addition of MNP-OA to liposomes, were evaluated by studying the leakage of carboxyfluorescein and of the co-encapsulated Tb/DPA complex. These assays allowed us to determine that MNP-OA did not significantly modify liposome permeability during the fusion process. Transmission electron microscopy and confocal microscopy revealed that MNP-OA remained embedded in the lipid bilayer without producing membrane rupture, liposome deformation, or destruction. In addition, we evaluated the effect of applying a low-intensity magnetic field to the LUVs/MNP-OA system and observed that the nanoparticles considerably increased their fusogenic activity under this external stimulus, as well as they are capable of responding to low magnetic fields of around 0.45 mT. These results revealed the potential of hydrophobic magnetic nanoparticles, stabilized with OA, to act as a fusogen, thus representing a valuable tool for biotechnological applications.

Deformation Dynamics of Giant Unilamellar Vesicles in the Large Surface-to-Volume Ratio Regime: The Emergence of Neuron-like Morphology.

Deformation of liposomes, or lipid vesicles, has been investigated extensively in terms of the thermodynamic equilibrium of the bending energy of the lipid bilayer membrane. However, the range of such deformation in previous literature has been limited within the moderate surface-to-volume ratio of the vesicles, in which axisymmetric shapes are dominant. Here, we show that neuron-like morphology, in which many lipid tubes extend radially from the mother vesicle, becomes dominant upon the slow osmotic shrinkage of giant unilamellar vesicles (GUVs) initially larger than several tens of micrometers. We show that, in the time-lapse confocal imaging, the emergence of lipid tubes is initiated from the instability that appeared along the annular rim of the flat stomatocyte shape. Since these deformation dynamics into the neuron-like morphology resemble that of the milk-crown formation in liquid splashing, we discuss that the Rayleigh-Plateau capillary instability drives this transformation into a nonaxisymmetric shape.

Lipid Membrane Deformation Induced by Transmembrane Peptides

The plasma membrane has an essential role in life activities of living cells. For example, the lipid membrane enables to enclose molecules in inner compartment to isolate from outer environment. Inner/outer molecules are sometimes exchanged by dynamic membrane deformation as endo- or exocytosis. Extensive proteins including membrane proteins complicatedly interact in the deformation event. Matrix-2 (M2) protein in influenza A virus mediates a part of infection pathway by budding and scission. It was reported that the partial sequence of M2 protein has the deformability to liposome which contains model cell-membrane. Besides, a few studies reported that melittin, one of antimicrobial peptides (AMPs), also induced liposome deformation, but the detailed mechanism of the deformation-induced peptides has been still unclear. In this study, as the first step to elucidate the mechanism, we focus on short membrane binding peptide, AMPs, and cell-penetrating peptides (CPPs), and evaluate their deformability. The AMPs are known as pore-formation in plasma membrane, and CPPs translates across the lipid membrane. In our experiments, we prepared liposome, added peptides to liposome solution, observed them by microscopy, and then performed the 2D shape-deforming analysis. Also, we developed planner lipid membrane and measured temporal membrane capacitance (Cm). In this paper, we will discuss on (a) these peptides have deformability (b) the deformability difference among each peptide. We believe that our methods will be a useful tool to elucidate the peptide deforming mechanism.

De novo synthesized Min proteins drive oscillatory liposome deformation and regulate FtsA-FtsZ cytoskeletal patterns

The Min biochemical network regulates bacterial cell division and is a prototypical example of self-organizing molecular systems. Cell-free assays relying on purified proteins have shown that MinE and MinD self-organize into surface waves and oscillatory patterns. In the context of developing a synthetic cell from elementary biological modules, harnessing Min oscillations might allow us to implement higher-order cellular functions. To convey hereditary information, the Min system must be encoded in a DNA molecule that can be copied, transcribed, and translated. Here, the MinD and MinE proteins are synthesized de novo from their genes inside liposomes. Dynamic protein patterns and accompanying liposome shape deformation are observed. When integrated with the cytoskeletal proteins FtsA and FtsZ, the synthetic Min system is able to dynamically regulate FtsZ patterns. By enabling genetic control over Min protein self-organization and membrane remodeling, our methodology offers unique opportunities towards directed evolution of bacterial division processes in vitro.

Deformation of Unilamellar Liposomes Induced by Evaporation of the Solvent

Deformation of Unilamellar Liposomes Induced by Evaporation of the Solvent

Disassembly of Dipeptide Single Crystals Can Transform the Lipid Membrane into a Network.

Coupling between cytoskeleton and membranes is critical to cell movement as well as organelle formation. Here, we demonstrate that self-assembled single crystals of a dipeptide, diphenylalanine (FF), can interact with liposomes to form cytoskeleton-like structures. Under a physiological condition, disassembly of FF crystals deforms and translocates supported lipid membrane. The system exhibits similar dynamic characteristics to the endoplasmic reticulum (ER) network in cells. This bottom-up system thus indicates that external matter can participate in the deformation of liposomes, and disassembly of the nanostructures enables a system with distinct dynamic behaviors.

Liposomal internal viscosity affects the fate of membrane deformation induced by hypertonic treatment.

Artificial lipid membranes have been utilized to understand the physical mechanisms of the deformation patterns of live cells. However, typical artificial membrane systems contain only dilute components compared to those in the cytoplasm of live cells. By using giant unilamellar liposomes containing dense protein solutions similar to those in live cells, we here reveal that viscosity derived from internal crowding affects the deformation patterns of lipid membranes. After hypertonic treatment, liposome deformation patterns transitioned from budding to tubing when the initial internal macromolecular concentrations were increased. Remarkably, instead of observing different transition concentrations between two species of macromolecules, the viscosity at the transition concentration was found to be similar. Further analyses clearly demonstrated that the internal viscosity affects the deformation patterns of lipid membranes induced by hypertonic treatment. These results indicate that the viscosity of the cytoplasm is a key factor in determining cell deformation, and suggest the association of a process involving dynamic instability, such as a viscous fingering phenomenon, during the determination of deformation patterns by hypertonic treatment.