A biomembrane's role is to be a barrier for interior cytosol from an exterior environment to execute the cell's normal biological functions. However, a water-soluble peptide called cell-penetrating ...peptide (CPP) has been known for its ability to directly penetrate through the biomembranes into cells (cytolysis) without perturbating cell viability and expected to be a promising drug delivery vector. Examples of CPP include peptides with multiple arginine units with strong cationic properties, which is the key to cytolysis. Here we show the conclusive evidence to support the mechanism of CPP's cytolysis and way to control it. The mechanism we proposed is attributed to biomembrane's physicochemical nature as lamellar liquid crystal (Lα). Cytolysis occurs as the temporal and local dynamic phase transitions from Lα to an undulated lamellar with pores called Mesh
. We have shown this phase transfer of Lα composed of dioleoyl-phosphatidylcholine (DOPC) with water by adding oligo-arginine (Rx) as CPP at the equilibrium. Using giant unilamellar vesicle composed of DOPC as a single cell model, we could control the level of cytolysis of CPP (FITC-R8) by changing the curvature of the membrane through osmotic pressure modulation. The cytolysis of CPP utilizes biomembrane's inherent topological and functional flexibility corresponding to the stimuli.
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•Morphological changes in surfactant mixtures were monitored using high-speed AFM.•Solution exchanges were examined in monomeric or monomeric/gemini systems.•Worm – bilayer ...transformations occurred in response to solution exchanges.•These morphological changes occurred reversibly within a few minutes.
We characterized time-dependent morphological changes in cationic monomeric/gemini surfactant mixtures adsorbed on silica using high-speed atomic force microscopy (HS-AFM). The gemini surfactant employed in this study was 1,2-bis(dodecyldimethylammonio)ethane dibromide (12-2-12). This surfactant was mixed with a monomeric surfactant, hexadecyltrimethylammonium bromide (HTAB), in the presence of a background electrolyte. The HS-AFM measurements revealed that wormlike surface aggregates that formed in an HTAB solution transformed into a bilayer within a few hundred seconds after the HTAB solution was replaced by an HTAB + 12-2-12 mixed solution. This morphological change was reversed within a few hundred seconds after this solution was replaced by the initial HTAB solution. These time-dependent morphological changes were supported by simultaneous quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry measurements. The energy dissipation, monitored by QCM-D, changed reversibly in response to the solution exchanges.
Photo-induced rapid control of molecular assemblies, such as micelles and vesicles, enables effective and on-demand release of drugs or active components, with applications such as drug delivery ...systems (DDS) and cosmetics. Thus far, no attempts to optimize the responsiveness of photoresponsive molecular assemblies have been published. We previously reported photoresponsive surfactants bearing a lophine dimer moiety that exhibit fast photochromism in confined spaces, such as inside a molecular assembly. However, rapid control of the micelle structures and solubilization capacity have not yet been demonstrated. In the present work, photo-induced morphological changes in micelles were monitored using in-situ small-angle neutron scattering (SANS) and UV/Vis absorption spectroscopy. An amphiphilic lophine dimer (3TEG-LPD) formed elliptical micelles. These were rapidly elongated by ultraviolet light irradiation, which could be reversed by dark treatment, both within 60 s. For a solution of 3TEG-LPD micelles solubilizing calcein as a model drug molecule, fluorescence and SANS measurements indicated rapid release of the incorporated calcein into the bulk solvent under UV irradiation. Building on these results, we investigated rapid controlled release via hierarchical chemical processes: photoisomerization, morphological changes in the micelles, and drug release. This rapid controlled release system allows for effective and on-demand DDS.
The current review covers recent advances on development and investigation of cationic surfactants containing imidazolium headgroup, which are being extensively investigated for their ...self-aggregation properties and are currently being utilized in various conventional and non-conventional application areas. These surfactants are being used as: soft template for synthesis of mesoporous/microporous materials, drug and gene delivery agent, stabilizing agent for nanoparticles, dispersants for single/multi walled carbon nanotubes, antimicrobial and antifungal agent, viscosity modifiers, preparing nanocomposite materials, stabilizing microemulsions, corrosion inhibitors and catalyst for organic reactions. Recently several structural derivatives of these surfactants have been developed having many interesting physicochemical properties and they have demonstrated enormous potential in the area of nanotechnology, material science and biomedical science.
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•Cationic surfactants containing positively charged imidazolium headgroup•Detailed synthetic schemes for synthesis of imidazolium surfactants•Discussion about various types of imidazolium surfactants•Self-aggregation and physicochemical properties of imidazolium surfactants•Detailed discussion about application area of imidazolium surfactants
Nanodiscs belong to a category of water-soluble lipid bilayer nanoparticles. In vivo nanodisc platforms are useful for studying isolated membrane proteins in their native lipid environment. Thus, the ...development of a practical method for nanodisc reconstruction has garnered consider-able research interest. This paper reports the self-assembly of a mixture of bio-derived cyclic peptide, surfactin (SF), and l-α-dimyristoylphosphatidylcholine (DMPC). We found that SF induced the solubilization of DMPC multilamellar vesicles to form their nanodiscs, which was confirmed by size-exclusion chromatography, dynamic light scattering, and transmission electron microscopy analyses. Owing to its amphiphilic nature, the self-assembled structure prevents the exposure of the hydrophobic lipid core to aqueous media, thus embedding ubiquinol (CoQ10) as a hydrophobic model compound within the inner region of the nanodiscs. These results highlight the feasibility of preparing nanodiscs without the need for laborious procedures, thereby showcasing their potential to serve as promising carriers for membrane proteins and various organic compounds. Additionally, the regulated self-assembly of the DMPC/SF mixture led to the formation of fibrous architectures. These results show the potential of this mixture to function as a nanoscale membrane surface for investigating molecular recognition events.
In this study, we aimed to control the recombination rate of lophyl radicals in micelles, which were produced from a lophine dimer by ultraviolet irradiation, formed by cationic surfactants with ...different alkyl chain lengths. The recombination rate in the micellar solution of the surfactant with a shorter alkyl chain was enhanced compared to that with a longer alkyl chain. Small-angle neutron scattering measurements showed that mixtures of the cationic surfactant and the lophine dimer derivative formed elliptical micelles, and a smaller inner volume was observed when shorter chain surfactants were used. Furthermore, evaluation of the kinetic parameters indicated that the randomness of the lophyl radical in the shorter surfactant micelle was higher than that in the longer surfactant micelle. These results revealed that the size of the confined space formed by the micelles determines the recombination rate of the lophyl radicals. This provides a new methodology for the development of volatile and nonvolatile molecular memories with arbitrary retention times and future quantum computing based on photochromic compounds.
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Perfume solubilization is an important process in the production of commercial products such as beverages, foods, and cosmetics. In the present study, small-angle neutron scattering (SANS) ...experiments were performed to investigate the solubilization behavior of perfumes in cetyltrimethylammonium bromide (CTAB) micelles. The solubilization of linalool (LL) and l-menthol (MT), which are relatively hydrophilic perfumes, did not change the size of the CTAB micelles although the perfumes were incorporated in the micelles, as indicated by a decrease in scattering length density. On the other hand, the solubilization of d-limonene (LN), a hydrophobic perfume, led to the swelling of CTAB micelles. An internal contrast variation SANS study was performed by the deuteration of CTAB molecules to directly observe the perfumes in the micelles. The radius of d-CTAB micelles solubilizing LL or MT corresponds to that of h-CTAB, which indicates that these perfumes are accommodated in the palisade layers of the micelles and are homogeneously distributed in the micelles. On the other hand, LN formed small droplets, as indicated by the SANS profile, which implies the solubilization of LN molecules in the core of the CTAB micelles. We found that the relatively hydrophilic perfumes (LL and MT) show less impact on the sizes of the cationic micelles in comparison to nonionic micelles. Thus, the internal contrast variation method of SANS allowed the direct observation of the solubilization sites of perfumes with different hydrophilicity–hydrophobicity balances. This method is a powerful tool to determine the solubilization states that affect the solubilization capacity, volatilization, or release speed of perfumes.
Cell-penetrating peptide (CPP) can directly penetrate the cytosol (cytolysis) and is expected to be a potent vector for a drug delivery system (DDS). Although there is general agreement that CPP ...cytolysis is related to dynamic membrane deformation, a distinctive process has yet to be established. Here, we report the key process and factors controlling CPP cytolysis. To elucidate the task, we have introduced trypsin digestion of adsorbed CPP onto giant unilamellar vesicle (GUV) to quantify the adsorption and internalization (cytolysis) separately. Also, the time-course analysis was introduced for the geometric calculation of adsorption and internalization amount per lipid molecule consisting of GUV. As a result, we found that adsorption and internalization assumed to occur successively by CPP molecule come into contact with membrane lipid. Adsorption is quick to saturate within 10 min, while cytolysis of each CPP on the membrane follows successively. After adsorption is saturated, cytolysis proceeds further linearly by time with a different rate constant that is dependent on the osmotic pressure. We also found that temperature and lipid composition influence cytolysis by modulating lipid mobility. The electrolyte in the outer media is also affected as a chemical mediator to control CPP cytolysis by following the Hoffmeister effect for membrane hydration. These results confirmed the mechanism of cytolysis as temporal and local phase transfer of membrane lipid from Lα to Mesh
, which has punctured bilayer morphologies.
Renewable ester functionalized oleic and stearic acid based imidazolium surfactants were synthesized and characterized using spectroscopic techniques. The new surfactants were investigated for their ...self-aggregation properties and biodegradability in aqueous solution. These fatty acid based surfactants were able to self-aggregate into micelles at lower concentration compared to conventional surfactants and were found to be readily biodegradable. The surface properties and biodegradation rate of these new renewable surfactants depend on the nature of the hydrophobic tail. The oleic acid based surfactant containing a double bond in the hydrophobic oleyl tail demonstrated a greater capability to reduce the surface tension of an aqueous solution along with a greater ability to undergo biodegradation compared to the saturated hydrophobic stearyl tail containing a stearic acid based surfactant.
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