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Various amphiphiles including surfactants and lipids have been designed and synthesized to improve and create new functionalities. In particular, the emergence of cell-like behaviors of giant vesicles (GVs) composed of synthetic lipids has drawn much attention in the development of chemical models for cells. The aim of this study was to measure temperature-dependent morphological changes of GVs induced by fragmentation and subsequent growth using hydrolysable cationic lipids having an amide linkage. Results from differential scanning calorimetry, fluorescence spectroscopy using an environment-responsive probe, and confocal Raman microscopy showed that the dynamics observed were due to changes in the vesicle membrane, including variation in the lipid composition, induced by thermal stimulation.

Using water-floating 3D-printed models, we investigated the dynamics of camphor boats, which are composed of a one-holed board and a camphor grain, under constraint conditions where a rod hooks the camphor boat on the water surface. When a camphor boat was connected to a water-floating disk or another camphor boat through a rod, we found that regular dynamics of the camphor boat appear and depend on the mobility restriction of the disk, the rod length, and the position of a slit of the camphor boat. We performed numerical simulations to reproduce the observed motions with theoretical models including constraint conditions.

Flow cytometric analysis revealed that the redistribution of components of a hybrid vesicular system composed of amphiphilic nicotinamide and its reduced form occurred associated with the emergence of nonlamellar aggregates that emitted an enhanced blue emission together with a green emission due to exciplex formation.

As a supramolecular micromachine with information flow, a giant vesicle (GV)-based artificial cell that exhibits a linked proliferation between GV reproduction and internal DNA amplification has been explored in this study. The linked proliferation is controlled by a complex consisting of GV membrane-intruded DNA with acidic amphiphilic catalysts, working overall as a lipo-deoxyribozyme. Here, we investigated how a GV-based artificial cell containing this lipo-deoxyribozyme responds to diverse external and internal environments, changing its proliferative dynamics. We observed morphological changes (phenotypic expression) in GVs induced by the addition of membrane precursors with different intervals of addition (starvation periods). First, we focused on a new phenotype, the &ldquo, multiple tubulated&rdquo, form, which emerged after a long starvation period. Compared to other forms, the multiple tubulated form is characterized by a larger membrane surface with a heavily cationic charge. A second consideration is the effect of the chain length of encapsulated DNA on competitive proliferation. The competitive proliferation among three different species of artificial cells containing different lengths of DNA was investigated. The results clearly showed a distinct intervention in the proliferation dynamics of the artificial cells with each other. In this sense, our GV-based artificial cell can be regarded as an intelligent supramolecular machine responding to external and internal environments, providing a new concept for developing molecular machines and robotics.

Design and fabrication of organic and polymeric soft materials exhibiting solvent-free isothermal changes in mechanical properties triggered by photostimulation are challenging. Here, we report dramatic changes in viscoelasticity of coumarin end-functionalized poly(dimethyl siloxane) with a branched macromolecular architecture under a solvent-free isothermal condition upon alternating irradiation of UV at the wavelength of 365 and 254 nm (UV365 and UV254). Significantly, it is disclosed that storage modulus (G′) was increased by a factor of more than 30000. Moreover, the subsequent UV254 irradiation caused sharp decrease in G′ and it became comparable to loss modulus. Furthermore, alternating irradiation of UV365 and UV254 caused repetitive increase and decrease in G′ of the material.

Micrometer-sized self-propelled oil droplets under a far-from-equilibrium condition have drawn much attention because of their potential as a dynamic model for the chemical machinery in living organisms. To clarify the effect of interactions between the system components (surfactant, oil, and water) on the locomotion mode of droplets, we investigated the behaviors of oil droplets composed of n-heptyloxybenzaldehyde (HBA) in solutions of cationic surfactants having or not having an ester or an ether linkage. It was observed that in solutions of cationic surfactants having an ester or an ether linkage, spherical HBA droplets self-propelled by changing their direction frequently. On the other hand, when this functional group is absent, a slow self-propelled motion of the oil droplets concurrent with the evolution of aggregates on their surface was observed. From the results of measurement of interfacial tension and assessment of self-emulsification, we determined that the attractive interactions of cationic surfactants without an ester or an ether linkage with HBA are stronger than those having the linkage. The difference in the locomotion mode of oil droplets is probably explained from the viewpoint of the interactions among the system components.

Solvent-free isothermal tuning of viscoelasticity of polymer materials is important for an emerging photochemical molding technology and photoreversible adhesives. In this study we designed a four-armed star-shaped poly(butyl acrylate, BA) oligomer having four coumarin end groups. The irradiation of UV at the wavelength of 365 nm (UV365) to the viscous poly(BA) oligomer under a solvent-free condition produced a solid network material along with the progress of dimerization reaction with coumarin end groups. The subsequent irradiation of UV at the wavelength of 254 nm (UV254) caused dimer dissociation reaction to attain change in the mixing degree of star and network architectures in the material. Moreover, viscoelasticity of the network material was tunable by repetitive UV365 and UV254 irradiations. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

The characteristic amoeboid behavior of an oil droplet (decane with dissolved palmitic acid) on an aqueous phase containing a surfactant (stearyltrimethylammonium chloride) has been investigated and discussed. The formation and motion of assemblies of molecular aggregates were observed with the aid of a range of particle tracers. The quasi-elastic laser scattering method was employed to measure the surface tension of the aqueous phase as a function of time. From those measurements we found that the amoeboid behavior occurs in three stages. First, molecular aggregates formed at the oil-water interface and subsequently spread and absorbed at the aqueous surface thanks to a convective flow due to the Marangoni effect. In the second stage, the whole aqueous surface was saturated with those molecular aggregates and a phase transition to a liquid condensed monolayer membrane occurred. Finally, domains formed at the bottom of the oil droplet with permeable boundaries composed of branch-shaped assemblies of molecular aggregates. Blebs grew in those parts of the oil droplet rim with high accumulation of molecular aggregates.

DNA is an essential carrier of sequence-based genetic information for all life today. However, the chemical and physical properties of DNA may also affect the structure and dynamics of a vesicle-based model protocell in which it is encapsulated. To test these effects, we constructed a polyethylene glycol-grafted giant vesicle system capable of undergoing growth and division. The system incorporates a specific interaction between DNA and lipophilic catalysts as well as components of PCR. We found that vesicle division depends on the length of the encapsulated DNA, and the self-assembly of an internal supramolecular catalyst possibly leads to the direct causal relationship between DNA length and the capacity of the vesicle to self-reproduce. These results may help elucidate how nucleic acids could have functioned in the division of prebiotic protocells.

Lipid-coated microbubbles (MBs) with an indocyanine green (ICG) derivative were fabricated for ultrasound and near-infrared (NIR) fluorescence dual imaging. We characterized the NIR-fluorescence intensity, stability and viscoelastic properties of the encapsulating lipid shell, focusing on the influence of the ICG derivative and lipid compositions. In terms of the NIR fluorescence intensity, the fluorescence intensity of the MBs (with the ICG derivative) was significantly affected by the lipid composition of the MB shell. Regarding the contrast agent used for ultrasound imaging, the stability of the MBs and viscoelastic properties of shell also depended on the lipid compositions, while the incorporation of the ICG derivative into the MB shells had a negligible effect. The performance of this contrast agent for ultrasound and NIR fluorescence dual-imaging exhibited a significant trade-off relationship for the lipid composition.

The self-reproduction of supramolecular assemblies based on the synthesis and self-assembly of building blocks is a critical step towards the construction of chemical systems with autonomous, adaptive, and propagation properties. In this report, we demonstrate that giant vesicles can grow and produce daughter vesicles by synthesizing and incorporating phospholipids in situ from ad-hoc precursors. Our model involves acyl chain elongation via copper(I)-catalyzed azide-alkyne [3 + 2] cycloaddition reaction and the ensuing production of synthetic phospholipids to induce budding and division. In addition, the growth and budding of giant vesicles were compatible with the encapsulation and transfer of macromolecules as large as lambda phage DNA to the buds. This chemical system provides a useful model towards the implementation of cell-like compartments capable of propagation and transport of biological materials.

Although the mechanical properties and compositions of lipid bilayer membranes can change upon deformation, the fundamental relations between the composition, membrane tension and fluidity of membranes with little curvature have not yet been studied. In the current study, the membrane tension and the diffusion coefficients of free-standing black lipid membranes (BLMs), based on 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), were observed by systematic control of the cholesterol concentration and the osmotic pressure with the laser-induced surface deformation (LISD) and fluorescence recovery after photobleaching (FRAP) techniques. When the osmotic pressure was raised and, therefore, the curvature became larger, both the membrane tension and the diffusion coefficients increased as well. On the other hand, when the cholesterol concentration was raised, the membrane tension increased whereas the diffusion coefficient decreased. The importance of the present results goes beyond this quantitative evaluation of the relation between the membrane tension and the fluidity, as it clarifies the changes in the fundamental properties of lipid bilayers upon natural fluctuations and perturbative deformation that were hitherto unknown.

Using a quasi-elastic laser scattering (QELS) method, we determined the changes in the interfacial tension of a lipid monolayer membrane, composed of either 1,2-dioleoyl-sn-glycero-3-phospho- l -serine sodium salt (DOPS) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), at the water/chloroform interface upon the addition of lysozyme. The measurements were performed in the presence of electrolytes of different concentrations and using lipids that vary the net charge of the monolayer membrane. As a result, the interfacial tension was observed to decrease in three stages. In the case of DOPS, there was a lag time wherein the interfacial tension did not change, which lasted from several tens of seconds to several hundreds, following electrostatic interaction between lysozyme and the lipid monolayer membrane. On the other hand, the DOPC monolayer membrane decreased its interfacial tension without such a lag time after lysozyme addition. The lag time was attributed to the strong electrostatic interaction between the lysozyme and the DOPS monolayer membrane, which delayed the hydrophobic interaction that causes a change in the overall structure and conformation of lysozyme and lipids.

We demonstrate a novel system that exhibits both self-propelled motion and division of micrometer-sized oil droplets induced by chemical conversion of the system components. Such unique dynamics were observed in an oil-in-water emulsion of a benzaldehyde derivative, an alkanol and a cationic surfactant at a low pH.

Knowing the exact location of gastrointestinal tumors both preoperatively and intraoperatively is essential for planning and performing laparoscopic surgery. Different techniques have been introduced to ascertain tumor locations during surgery, but none of these are fully satisfactory at establishing the minimum margins for organ resection while retaining curability. A new, non-blurring tissue marker, detectable by both X-ray computed tomography (CT) and near-infrared (NIR) fluorescence laparoscopy, has been developed, and we here examine its utility using an animal model. Liposomes, comprised phospholipids and an NIR fluorescent dye (an indocyanine green derivative), and emulsions, consisting of phospholipids and oily radiographic contrast medium, were combined with polyglycerol-polyricinoleate to form giant cluster-like vesicles. This vesicular dispersion (300 μl) was administered into the porcine gastric submucosa using a gastroendoscope, and the detectability of the marker was examined using X-ray CT and NIR fluorescence laparoscopy. One hour after the administration of the vesicular dispersion, X-ray CT identified four individual injection sites, each at a 1-cm radius of a metal hemostasis clip. NIR fluorescence laparoscopy detected individual fluorescent spots 18 hours after the administration of the vesicular dispersion. We anticipate that this newly developed tissue marker will contribute to the preoperative simulation of laparoscopic gastrointestinal cancer surgery and its intraoperative navigation.

Self-propelled motion of micrometer-sized substances has drawn much attention as an autonomous transportation system. One candidate vehicle is a chemically driven micrometer-sized oil droplet. However, to the best of our knowledge, there has been no report of a chemical reaction system controlling the three-dimensional motion of oil droplets underwater. In this study, we developed a molecular system that controlled the self-propelled motion of 4-heptyloxybenzaldehyde oil droplets by using novel gemini cationic surfactants containing carbonate linkages (2G12C). We found that, in emulsions containing sodium hydroxide, the motion time of the self-propelled oil droplets was longer in the presence of 2G12C than in the presence of gemini cationic surfactants without carbonate linkages. Moreover, in 2G12C solution, oil droplets at rest underwent unidirectional, self-propelled motion in a gradient field toward a higher concentration of sodium hydroxide. Even though they stopped within several seconds, they restarted in the same direction. 2G12C was gradually hydrolyzed under basic conditions to produce a pair of the corresponding monomeric surfactants, which exhibit different interfacial properties from 2G12C. The prolonged and restart motion of the oil droplets were explained by the increase in the heterogeneity of the interfacial tension of the oil droplets.

Liposomally formulated indocyanine green (LP-ICG) has drawn much attention as a highly sensitive near-infrared (NIR)-fluorescence probe for tumors or lymph nodes in vivo. We synthesized ICG derivatives tagged with alkyl chains (ICG-Cn), and we examined NIR-fluorescence imaging for lymph nodes in the lower extremities of mice by using liposomally formulated ICG-Cn (LP-ICG-Cn) as well as conventional liposomally formulated ICG (LP-ICG) and ICG. Analysis with a noninvasive preclinical NIR-fluorescence imaging system revealed that LP-ICG-Cn accumulates in only the popliteal lymph node 1h after injection into the footpad, whereas LP-ICG and ICG accumulate in the popliteal lymph node and other organs like the liver. This result indicates that LP-ICG-Cn is a useful NIR-fluorescence probe for noninvasive in vivo bioimaging, especially for the sentinel lymph node.

Tip-enhanced Raman spectroscopy (TERS) of supported phospholipid bilayers in an aqueous environment is discussed in this paper. Two bilayer membranes were examined: 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). We fabricated alumina- and silver-coated tungsten tips that are very robust in water. There was a large time-dependence in the TERS spectra for the DOPC bilayers, whereas no such time-dependence was observed in the DPPC bilayer spectra under the probe tip. The spectral changes of DOPC bilayers are discussed in terms of the fluidity of the liquid crystalline phase. Time-resolved TERS thus has the potential to characterize inhomogeneity and diffusion in fluidic phospholipid bilayer membranes.

Background: The transformation of the supported lipid bilayer (SLB) membrane by extracted cytosol from living resources, has recently drawn much attention. It enables us to address the question of whether the purified phospholipid SLB membrane, including lipids related to amoeba locomotion, which was discussed in many previous studies, exhibits membrane deformation in the presence of cytosol extracted from amoeba; Methods: In this report, a method for reconstituting a supported lipid bilayer (SLB) membrane, composed of purified phospholipids and cytosol extracted from Dictyostelium discoideum, is described. This technique is a new reconstitution method combining the artificial constitution of membranes with the reconstitution using animate cytosol (without precise purification at a molecular level), contributing to membrane deformation analysis; Results: The morphology transition of a SLB membrane composed of phosphatidylcholines, after the addition of cytosolic extract, was traced using a confocal laser scanning fluorescence microscope. As a result, pore formation in the SLB membrane was observed and phosphatidylinositides incorporated into the SLB membrane tended to suppress pore formation and expansion; Conclusions: The current findings imply that phosphatidylinositides have the potential to control cytoplasm activity and bind to a phosphoinositide-containing SLB membrane.

Unique dynamics using inanimate molecular assemblies based on soft matter have drawn much attention for demonstrating far-from-equilibrium chemical systems. However, there are no soft matter systems that exhibit a possible pathway linking the self-propelled oil droplets to formation of giant vesicles stimulated by low pH. In this study, we conceived an experimental oil-in-water emulsion system in which flocculated particles composed of a imine-containing oil transformed to spherical oil droplets that self-propelled and, after coming to rest, formed membranous figures. Finally, these figures became giant vesicles. From NMR, pH curves, and surface tension measurements, we determined that this far-from-equilibrium phenomenon was due to the acidic hydrolysis of the oil, which produced a benzaldehyde derivative as an oil component and a primary amine as a surfactant precursor, and the dynamic behavior of the hydrolytic products in the emulsion system. These findings afforded us a potential linkage between mobile droplet-based protocells and vesicle-based protocells stimulated by low pH.

We have rationally designed and synthesized a novel near-infrared (NIR) photoactivating probe, designated by iDOPE, in which an indocyanine green (ICG) fluorophore is covalently conjugated with a phospholipid moiety, 1,2-dioleoyl- sn -glycero-3-phosphoethanolamine (DOPE), to incorporate into liposome bilayers. NIR irradiation showed that iDOPE retained the optical and fluorescence properties of ICG and demonstrated photoactivator characteristics: fluorescence emission at around 820 nm in a solvent, singlet oxygen production, and concentration-dependent heat generation. Additionally, iDOPE was incorporated into liposome bilayers and maintained stable liposomally formulated iDOPE (LP-iDOPE) over 1 week under physiological conditions. We also observed the tumor-specific biodistribution of LP-iDOPE of in vivo xenografts. These findings suggest that LP-iDOPE might be a promising tool for NIR optical imaging, photodynamic therapy, and photothermal therapy.

Self-propelled oil droplets in a nonequilibrium system have drawn much attention as both a primitive type of inanimate chemical machinery and a dynamic model of the origin of life. Here, to create the pH-sensitive self-propelled motion of oil droplets, we synthesized cationic surfactants containing hydrolyzable ester linkages. We found that n-heptyloxybenzaldehyde oil droplets were self-propelled in the presence of ester-containing cationic surfactant. In basic solution prepared with sodium hydroxide, oil droplets moved as molecular aggregates formed on their surface. Moreover, the self-propelled motion in the presence of the hydrolyzable cationic surfactant lasted longer than that in the presence of nonhydrolyzable cationic surfactant. This is probably due to the production of a fatty acid by the hydrolysis of the ester-containing cationic surfactant and the subsequent neutralization of the fatty acid with sodium hydroxide. A complex surfactant was formed in the aqueous solution because of the cation and anion combination. Because such complex formation can induce both a decrease in the interfacial tension of the oil droplet and self-assembly with n-heptyloxybenzaldehyde and lauric acid in the aqueous dispersion, the prolonged movement of the oil droplet may be explained by the increase in heterogeneity of the interfacial tension of the oil droplet triggered by the hydrolysis of the ester-containing surfactant.

The distribution of surface tension on the front and rear sides of a camphor boat continuously moving on an aqueous-phase camphor solution was observed by the time-resolved quasi-elastic laser scat...

This review covers the drastic morphological changes, including division or birthing dynamics, and even spontaneous movements performed by molecular self-assemblies constructed by reactive amphiphiles with the imine group that connects hydrophilic and hydrophobic moieties. It turns out that the formation (dehydrocondensation) of such amphiphiles or their cleavage (hydrolysis) into individual moieties occurs depending on the reaction fields, such as in membranes, or at interfaces between water and selfassemblies constructed by the amphiphiles. Moreover these chemical conversions induce outstanding dynamics aforementioned. Hence these findings give a hint to understand hierarchical dynamics occurring in a living system.

Directional migration of neuronal cells over long distances is critical for the developing and regenerating nervous system. A scaffold, which includes radial glia, provides a route between the germinal zone and the destination, with the direction of migration being attributed mainly to chemotaxis. However, the decrease in chemokine concentration with distance complicates cell guidance control over long distances. Our working hypothesis is that neuronal cells migrate directionally on an anisotropic and periodic scaffold. We tested this in a model involving neuronal PC12 cells cultured in a ratchet wheel-shaped microchamber. The microchamber was constructed by printing a patterned, thin film of polydimethylsiloxane (PDMS), to which the cells adhere weakly, onto a collagen-coated dish, to which the cells adhere strongly, using a microcontact printing technique. The cells can attach, extend neurites, and migrate on the anisotropic and periodic collagen-coated area between the ratchet wheel-shaped outer frame and round inner frame of the PDMS. We found that the microchamber geometry affected the direction of migration, even though the mean length of the longest neurite was independent of microchamber geometry. The time-course trace of cell body migration and neurite tips showed that the neurite tips remained around the tips of the ratchet teeth. These results suggested that neuronal cells migrate directionally on a scaffold, even in the absence of chemokine, and reveal a new conceptual framework for neuronal migration.

Non-invasive measurement of the membrane tension of free-standing black lipid membranes (BLMs), with sensitivity on the order of μN m(-1), was achieved using laser-induced surface deformation (LISD) spectroscopy. A BLM was vertically formed via the folding method and aqueous phases with different refractive indices were added on each side in order to induce radiation pressure by a laser beam. The dynamic response of the deformed BLMs was measured under periodic intensity modulation and their tensions could be estimated. The dependence of membrane tension on the cholesterol concentration of BLMs composed of phosphatidylcholine and phosphatidylethanolamine was investigated, with the membrane tension increasing from 1.3 μN m(-1) to 68.1 μN m(-1) when the cholesterol concentration increased from zero to 33%. These tension values are much smaller than some of those previously reported, because this method does not suppress membrane fluctuation unlike other conventional methods. Our LISD system can be a promising tool for the measurement of membrane tension in BLMs.

We have developed a novel lipid-bearing DNA that forms hairpin modules, including a single RNA monomer; this can be used to create micrometer-sized structures from nanometer-sized building blocks during breakage at the RNA site. In the presence of divalent metal ions and heat stimulation, we observed transition of the self-assembly, which results in the formation of a three-dimensional network structure. To our knowledge, this is also the first report of heat-induced micrometer-sized molecular self-assembly of molecules that carry biological information.

A morphological transformation from hybrid micelles to giant vesicles was observed in aqueous dispersion associated with formation of a double-chained amphiphile as a result of the migration of dodecylamine from the amphiphilic imine to the amphiphilic aldehyde within the hydrophobic environment of amphiphilic aggregates.

Non-blurring tissue marker detectable by both X-ray computed tomography (CT) and near-infrared fluorescence laparoscope (NIR-FL) was newly developed to localize gastrointestinal tumors both preoperatively and intraoperatively, and its usefulness was examined with an animal model. Hydrophobic NIR fluorophore and ethiodized oil were aggregated with polyglycerol polyricinoleate into polymersome. This aggregate of 300 ml was administered into the porcine stomach using gastroendoscope, and CT and NIR-FL were performed. Four injection points within a 1-cm radius were individually identified with both modalities immediately and 18 h after administration. This dual-imaging marker could contribute to both preoperative simulation and intraoperative navigation for laparoscopic gastrointestinal surgery.

In this study, we describe the development of a novel tissue marker that can be injected from within the digestive tract by using an endoscopic instrument, and visualized using near-infrared (NIR) fluorescence imaging. The marker was prepared in three steps, (i) mixing NIR-fluorescent indocyanine green (ICG) with giant vesicles (GVs) of lecithin, (ii) suspending the ICG-containing giant vesicles (ICG-GV) in an oil phase dissolving polyglycerol-polyricinoleate (PGPR), and (iii) centrifugation of the suspension layered on a buffered solution to obtain a giant polymer vesicle (polymerasome) containing ICG-GV. We injected the tissue marker into the inner gastric surface of an anesthetized pig using an endoscopic syringe, and observed the injection site using a fluorescence laparoscopic camera. The diameter of the spot blur was approximately 2 cm over a 5-h period, demonstrating the utility of this procedure as a tissue marker for tumor marking, and suggesting its potential for assisting navigation during surgical procedures.

Amoeboid locomotion is one of the fundamental modes of cell motion that accompanies dynamic deformation of plasma membrane. From yeast to human cell, localized activation of small GTPase and phosphatidylinositol signaling initiates breaking of intracellular symmetry and are thought to play critical roles in generating polarized membrane extension and retraction. Although it is generally believed that some forms of reaction-diffusion driven mechanisms underlie these “symmetry breaking” events, the physicochemical basis of its onset, i.e. autonomous nucleation events of the localized signaling patches and actin polymerization remains unclear. Here, we report on the behavior observed in our “two-dimensional reconstituted-system” consisting of a cytosolic extract and a solid-supported lipid membrane. We tested whether the solid-supported lipid membrane in a microchamber containing cytosol extracted by Dictyostelium discoideum provides an appropriate microenvironment for localized signaling by observing translocation of PH-domain protein and PTEN which were tagged with RFP and GFP respectively. Signal intensities were analyzed by a confocal laser scanning fluorescence and bright field microscopy. We found that both the PH-domain protein and PTEN attached to the membrane composed of both lipid extract and 2- or 3- component lipid mixture. In the case of lipid extract membrane, inhomogeneous domain formation of micrometer scale was observed. We examined the effect of several inhibitors related phosphatidylinositol signaling and found different patterning of the lipid membranes. We will discuss how the current system may be employed to address the origin of self-organized PIP2/PIP3 patches during amoeboid deformation.

We used a time-resolved interfacial tension measurement method with quasi-elastic laser scattering to investigate the effects of electrolytes and various surfactants on the nonlinear dynamics of the chemical oscillation that occurred at a water/nitrobenzene interface when a surfactant was added to the interface through a capillary. For both cationic and anionic surfactants, an electrolyte in the water phase was required for slow desorption of the surfactant from the interface. In the absence of an electrolyte, repulsion between the polar head groups of the ionic surfactants hindered adsorption of the surfactant molecules at the interface, resulting in their rapid desorption. In contrast, the presence of an electrolyte induced adsorption of the surfactant ions by screening their charged polar heads. Zwitterionic and nonionic surfactants were also examined and we deduced that the salting out effect of the surfactant produced by the presence of an electrolyte results in strongly attractive interactions between the surfactant molecules and the water/nitrobenzene interface.

Micrometer-sized self-propelled oil droplets in nonequilibrium systems have attracted much attention, since they form stable emulsions composed of oil, water, and surfactant which represent a primitive type of inanimate chemical machinery. In this work, we examined means of controlling the movement of oil droplets by studying the dynamics of n-heptyloxybenzaldehyde droplets in phosphate buffers containing alkanediyl-α,ω-bis(N-dodecyl-N,N-dimethylammonium bromide) (nG12) with either tetramethylene (4G12), octaethylene (8G12), or dodecamethylene (12G12) chains in the linker moiety. Significant differences in droplet dynamics were observed to be induced by changes in the linker structure of these gemini cationic surfactants. In a phosphate buffer containing 30 mM 4G12, self-propelled motion of droplets concurrent with the formation of molecular aggregates on their surfaces was observed, whereas the fusion of oil droplets was evident in both 8G12 and 12G12 solutions. We also determined that the surface activities and the extent of molecular self-assembly of the surfactants in phosphate buffer were strongly influenced by the alkyl chain length in the linker moiety. We therefore conclude that the surface activities of the gemini cationic surfactant have important effects on the oil-water interfacial tension of oil droplets and the formation of molecular aggregates and that both of these factors induce the unique movement of the droplets.

The construction of a protocell from a materials point of view is important in understanding the origin of life. Both self-reproduction of a compartment and self-replication of an informational substance have been studied extensively, but these processes have typically been carried out independently, rather than linked to one another. Here, we demonstrate the amplification of DNA (encapsulated guest) within a self-reproducible cationic giant vesicle (host). With the addition of a vesicular membrane precursor, we observe the growth and spontaneous division of the giant vesicles, accompanied by distribution of the DNA to the daughter giant vesicles. In particular, amplification of the DNA accelerated the division of the giant vesicles. This means that self-replication of an informational substance has been linked to self-reproduction of a compartment through the interplay between polyanionic DNA and the cationic vesicular membrane. Our self-reproducing giant vesicle system therefore represents a step forward in the construction of an advanced model protocell.

We have developed a method to evaluate the fusion process of giant vesicles using a fluorescence-activated cell sorter (FACS). Three fluorescent markers and FACS technology were used to evaluate the extent of association and fusion of giant vesicles. Two fluorescent markers encapsulated in different vesicle populations were used as association markers; when these vesicles associate, the two independent markers should be observed simultaneously in a single detection event. The quenched fluorescent marker and the dequencher, which were encapsulated in separate vesicle populations, were used as the fusion marker. When the internal aqueous solutions mix, the quenched marker is liberated by the dequencher and emits the third fluorescent signal. Although populations of pure POPC vesicles showed no detectable association or fusion, the same populations, oppositely charged by the exogenous addition of charged amphiphiles, showed up to 50% association and 30% fusion upon population analysis of 100,000 giant vesicles. Although a substantial fraction of the vesicles associated in response to a small amount of the charged amphiphiles (5% mole fraction compared to POPC alone), a larger amount of the charged amphiphiles (25%) was needed to induce vesicle fusion. The present methodology also revealed that the association and fusion of giant vesicles was dependent on size, with larger giant vesicles associating and fusing more frequently.

This review covers the drastic morphological changes, including division or birthing dynamics, and even spontaneous movements performed by molecular self-assemblies constructed by reactive amphiphiles with the imine group that connects hydrophilic and hydrophobic moieties. It turns out that the formation (dehydrocondensation) of such amphiphiles or their cleavage (hydrolysis) into individual moieties occurs depending on the reaction fields, such as in membranes, or at interfaces between water and selfassemblies constructed by the amphiphiles. Moreover these chemical conversions induce outstanding dynamics aforementioned. Hence these findings give a hint to understand hierarchical dynamics occurring in a living system.

The interface of a biphasic system of water and nitrobenzene exhibits a rapid flip motion and a tangential flow, so-called Marangoni convection, accompanying a pulse-like change of interfacial electrical potential when an aqueous solution of sodium alkylsulfate is introduced to the interface through a capillary. Although it is conventionally known that the Marangoni convection is triggered by heterogeneity of the interfacial tension, the heterogeneity of the interfacial tension of this system has not been directly measured. Here, we employed a time-resolved quasi-elastic laser scattering method with a time resolution of 200 ms to trace the time course of the interfacial tension at the water/nitrobenzene interface, and we demonstrated the first experimental evidence for the heterogeneity of the interfacial tension. Moreover, we found that the homogeneity of interfacial tension was restored within 1 s and that, in the presence of an electrolyte in the water phase, the surfactant molecules were homogeneously adsorbed on the interface immediately after they were conveyed by the tangential flow at the interface, whereas in the absence of electrolyte, the surfactant molecules were distributed only in the bulk phases.

Giant vesicles (GVs) encapsulating colloidal particles by a specific volume fraction show a characteristic configuration under a hypertonic condition. Several flat faces were formed in GV membrane with orderly array of inner particles. GV shape changed from the spherical to the asymmetrical polyhedral configuration. This shape deformation was derived by entropic interaction between inner particles and GV membrane. Because a part of inner particles became to form an ordered phase in the region neighboring the GV membrane, free volume for the other part of particles increased. Giant vesicles encapsulating colloidal particles were useful for the model of “crowding effect” which is the entropic interaction in the cell.

Introduction Photodynamic therapy (PDT) is a less invasive option for cancer treatment that has evolved through recent developments in nanotechnology. We have designed and synthesized a novel liposome system that includes an indocyanine green (ICG) derivative, ICG-C18, in its bilayer. In addition to its use as an optical imager to visualize blood, lymphatic, and bile flow, ICG has also been used as an optical sensitizer. In the present report, we evaluate the use of our novel liposome system, LP-ICG-C18, in PDT for squamous cell carcinoma in an autologous murine model. Materials and Methods An excitation pulse beam (300 μJ/pulse) of a single band (800 nm) was used for sensitization. The cytotoxicity of the photodynamic therapy was evaluated in terms of cellular morphology changes, methyl thiazolyl tetrazolium (MTT) assay results, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) staining. We tested the enhanced permeability and retention effect of LP-ICG-C18 in tumor-bearing C3H/He mice using a near-infrared fluorescence imaging system and fluorescence microscopy. We also examined the antitumor effect of PDT by measuring tumor volume in tumor-bearing mice. Results Cell death and apoptosis were only observed in the PDT group receiving LP-ICG-C18. LP-ICG-C18 itself had no cytotoxic activity and showed good biocompatibility. LP-ICG-C18 accumulated on the tumor 24 hours after injection and was retained for approximately 3 weeks. Tumor cell apoptosis following PDT with LP-ICG-C18 was also observed under optical microscopy, MTT assay, and TUNEL staining. Conclusion These findings suggest that LP-ICG-C18 may be an effective intervening material in PDT for malignant disease.

Adding an artificial bolaamphiphile to a dispersion of giant multilamellar vesicles (GMVs) made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) induced a cup-shaped deformation in GMVs accompanied by partial extrusion of the inner vesicle; thereafter, the deformed vesicles returned to their original shape. On the other hand, when the artificial bolaamphiphile together with a surfactant was added to the vesicular dispersion, these deformation and reformation dynamics were transmitted from the outer membranes in GMVs to the inner membranes until an intact inner vesicle was extruded out of the outer membrane. The microscopic aspects of these processes were investigated using amphiphiles tagged with individual fluorophores.

Novel self-reproducing giant vesicles, consisting of a vesicular amphiphile with an imine group in its hydrophobic chain, were constructed. This vesicular amphiphile, the product of a dehydrocondensation reaction between amphiphilic aldehyde and a lipophilic aniline derivative, could be prepared within the giant vesicles. When a protected form of the aldehyde precursor was added to a suspension of giant vesicles containing the lipophilic aniline precursor and a catalyst, dehydrocondensation between the two precursors took place inside the vesicles and produced the same amphiphile as the one which constitutes the original vesicle. The newly formed amphiphiles self-assembled in the inner water pool to form small vesicles, which were eventually extruded through the outer layer of the original vesicle to the bulk water. Accordingly, this kinetic system can be designated as a self-reproducing system of giant vesicles.

It is found that helical structures can be formed by a simple achiral fatty acid, oleic acid, in the pH range of 8.0–8.1 at room temperature. Moreover, we succeeded in the first observation of spon...

An aqueous dispersion of the ammonium amphiphile with a Schiff-base segment exhibited the formation and decomposition of giant vesicles with diameters of several micrometers 2–4 h after the prepara...

The present study provides evidence that a kind of nucleic acid base crystal, guanine crystal, shows a distinct magnetic orientation. Under the condition where the guanine crystal boards were lying on the glass surface due to gravity, the boards gradually oriented their length to the applied horizontal magnetic fields of 400 mT. On the other hand, the vertical magnetic fields parallel to Earth's gravity caused their width to be oriented along the applied magnetic fields. Moreover, combining both vertical and horizontal magnetic fields produced a rapid alignment of the length to the horizontal magnetic fields.