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Lipopeptides are an exceptional example of amphiphilic molecules that self-assemble into functional structures with applications in the areas of nanotechnology, catalysis or medicinal chemistry. Herein, we report a library of 21 short lipopeptides, together with their supramolecular characterization and antimicrobial activity against both Gram-negative (E. coli) and Gram-positive (S. aureus) strains. This study shows that simple lipoamino acids self-assemble into micellar or vesicular structures, while incorporating dipeptides capable of stablishing hydrogen bonds results in the adoption of advanced fibrilar structures. The self-assembly effect has proven to be key to achieve antimicrobial activity., This project received funding from the La Caixa Foundation under the Junior Leader Program (No. LCF/BQ/PI19/11690020, ID 100010434), CAM-Atracción de Talento (2019-T1/IND-12683) and Spanish MICINN (PID2019-106327GA-I00). I. C. holds a Ramón y Cajal fellowship from Spanish MICINN (RyC2019- 026674-I). We also thank Prof. Isabel Rodriguez (IMDEA-Nanociencia) for providing bacterial strains and Dr Jose Miguel González (ICB-CSIC) for helping with the microscopy analysis

Amphiphilic molecules (e.g. hydrotropes) that enhance the solubility of hydrophobic compounds in water are often charged. As a result, such compounds also show specific ion effects. These effects can either strengthen or weaken the solubilisation power of amphiphilic molecules, depending on their degree of ion hydration. They can even prevail and transform an apparent solubilizer into an "anti-hydrotrope", i.e. a salting-out agent. In the present paper, we discuss this subtle balance between specific (Hofmeister) effects exerted by ionic headgroups and the hydrophobicity of the residual compound structure, including the size of the molecule and the presence of electron-withdrawing groups.

Unconventional life forms based on membranes able to self-assemble in hydrocarbons instead of water might in principle exist in the hydrocarbon-rich environments on Earth and in the methane lakes of Saturn's moon, Titan. This reversed paradigm for life would require that these membranes should be constituted of “reverse” surfactants. We here describe the synthesis of reverse amphiphilic molecules with a geometry similar to conventional surfactants but with an opposite topological configuration: lipophilic heads and lipophobic tails. Their self-assembly in cyclohexane was studied by 1H 2D DOSY-NMR and SAXS. We present experimental evidence of the self-assembly of these reverse surfactants to yield typical micelles in a hydrocarbon solvent.

Autofluorescent micelles were constructed via the self-assembly of amphiphilic molecules containing an intrinsic fluorophore. The amphiphilic molecule was an AIE-active luminogen without a conventional π-π conjugated structure. In this unconventional luminogenic system, the hydrogen-bonded amide groups were assigned as the emitting sources.

Solvent-dependent self-assemblies of an amphiphilic molecule based on perylene bisimide were employed in the fabrication of well-defined millimeter long nanorods and high density nanofibers, respectively. Moreover, the fabricated memory device demonstrated good behaviours with a low operating voltage, high ON/OFF ratio, long retention time, and good stability.

The micellization of amphiphilic molecules is an important phenomenon in the natural world. However, the origin of entropy change during micellization is still unclear. Molecular dynamics simulation was applied to study configurational entropy change of amphiphilic molecules in micellization. The entropy change of polar heads, hydrophobic chains, vibration, translation and rotation are discussed. Analyses provide a clear physical picture of the entropy increase in micellization, and thus foundations for further study.

Carbon nanotubes were functionalized with budesonide, a potent anti-inflammatory drug, and investigated for interactions with macrophages. Pristine carbon nanotubes were first shortened to make them compatible with cellular dimensions before budesonide was non-covalently appended to their surface via a specifically designed amphiphilic molecule. The resulting nanohybrids were evaluated in regards to their internalisation into macrophages and ability to inhibit pro-inflammatory cytokine secretion. In vitro experiments showed that the budesonide delivery system is readily captured by phagocytic cells and has a deep anti-inflammatory effect as it strongly inhibits IL-6 production.

Critical micelle concentration (CMC) is a key factor in applications of amphiphilic molecules, as it dictates the assembly state of the molecules. Nile Red (NR) is often used as a fluorogenic dye for the measurement of CMC values, but we have observed that NR is prone to aggregation, which leads to reduced reliability in CMC measurements. Here we evaluate 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO) as an alternative fluorogenic dye for the measurement of CMC values. Both NR and DiO provide values comparable to those reported in the literature. However, we demonstrate that DiO provides improved consistency and is more user friendly than NR for measurement of CMC values.

An amphiphilic molecule (Azo-Cl) was successfully synthesized and found to be able to construct reversible spherical vesicles in water. The assembled vesicles disappeared on the addition of equimolar α-cyclodextrin (α-CD) and reformed with UV irradiation due to the exclusion of the cis-azobenzene (Azo) group from α-CD’s hydrophobic cavity. With Vis irradiation, the vesicles were demolished again as α-CD combined with the Azo group again. These reversible photo-responsive vesicles based on the complexation between Azo-Cl and α-CD should be ideal switchable biomimetic membranes or carriers for photo-controllable release of functional matters like drugs.

Triblock amphiphilic molecules composed of three distinct segments provide a large parameter space to obtain self-assembled structures beyond what is achievable with conventional amphiphiles. To obtain a molecular understanding of the thermodynamics of self-assembly, we develop a coarse-grained triblock polymer model and apply self-consistent field theory to investigate the packing mechanism into layer structures. By tuning the structural and interaction asymmetry, we are able to obtain bilayers and monolayers, where the latter may additionally be mixed (symmetric) or segregated (asymmetric). Of particular interest for a variety of applications are the asymmetric monolayers, where segregation of end blocks to opposite surfaces is expected to have important implications for the development of functional nanotubes and vesicles with distinct surface chemistries.

Natural or synthetic amphiphilic molecules in solutions can self-assemble to form variably-scaled structures such as micelles, discs, vesicles, tubes and fibers. Minor changes in the conformation and characteristics of amphiphiles can greatly adjust the packing parameters (P = v/a0l0) and, in turn, the microstructures and the macroscopic properties of self-assembled systems, i.e., viscosity and elasticity, in some cases leading to a phase transition of spontaneous aggregates. This review focuses on how to controllably tune the phase transition of aggregates by changing the external conditions, e.g., pH, temperature, light, and ionic strength. Recent progress in the phase transition of assembled structures induced by external stimuli is summarized. We do not attempt a comprehensive description of studies reported in the literature, but rather focus on those advances that come from our laboratory, which aim to give a comprehensive understanding of stimuli-responsive intelligent systems, including the transition process, transition mechanism and applications, and thus to provide a guideline for the preparation of smart systems and practical applications.

We propose an important paradigm shift in the preparation of functional materials with well-designed nanostructures, from the nanotechnological to the nanoarchitectonic approach. Nanoarchitectonics is a methodology for arranging nanoscale structural units in the required configurations for new functional materials by the sophisticated combination and harmonization of several processes including atom/molecule manipulation, chemical nanomanipulation, field-induced materials control and controlled supramolecular self-assembly. In particular, nanoarchitectonics bears features of nanoscale phenomena including their flexibility and uncertainty of structure due to the unavoidable influence of thermal fluctuation. It shares characteristics with structural constructions in biological systems and could become a powerful bioinspired approach for materials science. Here, we focus on examples involving drug delivery functions due to these promising applications of bioinspired materials research. We commence with a discussion of recent developments involving assemblies of small amphiphilic molecules, polymer micelles and molecular conjugates and follow this with examples of challenging concepts including inorganic nanostructure design for drug delivery and mechanically controlled drug release. The new concept of bioinspired nanoarchitectonics could significantly expand the possibilities of systems design for drug delivery.

This critical review focuses on the origins and preparation of bio-based surfactants, defined here as non-soap, amphiphilic molecules in which the carbon atoms are derived from annually renewable feedstocks. Environmental concerns and market pressures have led to greater relevance of these chemicals in commercial applications in recent years and extensive research has gone into exploring new classes of surfactants. Highlighted here are examples of bio-based surfactants that are produced on an industrial scale and/or are based on abundant starting materials. The trend of increasing use of renewable resources as starting materials for surfactants is introduced, followed by extensive discussion of the major classes of bio-derived hydrophobes and hydrophiles. Also discussed is the status of research and development with regard to biosynthetically produced surfactants. Finally, concluding remarks address the potential for new surfactant molecular structures as a result of ongoing development in the chemistry of biorefineries, i.e., that the transformation of lignocellulose into fuels is likely to support the manufacturing of new bio-based coproducts (238 references).

We present large-scale simulation results on the self-assembly of amphiphilic systems in bulk solution and under soft confinement. Self-assembled unilamellar and multilamellar vesicles are formed from amphiphilic molecules in bulk solution. The system is simulated by placing amphiphilic molecules inside large unilamellar vesicles (LUVs) and the dynamic soft confinement-induced self-assembled vesicles are investigated. Moreover, the self-assembly of sickle hemoglobin (HbS) is simulated in a crowded and fluctuating intracellular space and our results demonstrate that the HbS self-assembles into polymer fibers causing the LUV shape to be distorted.

Dissipative particle dynamics simulations are used to investigate the structure of the columnar phases in T- and X-shaped bolaamphiphiles. These amphiphilic molecules consist of a rod-like aromatic core, with a polar group at each end. A single lateral chain is present in the T-shaped molecules and two lateral chains are present for X-shaped molecules. The simulations indicate that both types of molecules exhibit square and hexagonal columnar phases, in which the walls of the columns are formed by the aromatic core, the polar groups are located at the edges and the lateral chains fill the interiors of the columns. For the T-shaped molecules, the columns are always double walled. In contrast, for the X-shaped molecules, the columnar phases are single walled, in agreement with X-ray diffraction studies.

Amphiphilic molecules can self-assemble into a variety of aggregates and mesophases. Yet, predictions of phase transitions are not always met. In this communication, we demonstrate a novel structural phase transition of amphiphilic molecules, quillaja saponin/cholesterol, and discuss the relevance of precursors for forming hierarchical structures. In contrast to the standard sphero-cylinder model, we highlight a three-stage dynamic process of reentrant phase transition induced by cholesterol. It is expected that the obtained results would be helpful to rationalize the rich phase behavior exhibited by surfactant–cosurfactant systems, and to engineer complex nanoarchitectures with tunable size and shape and well-defined biological functions.

A miniscule amount of f-SWNTs remarkably improved (~17-fold) the gelation efficiency of amphiphilic molecules by triggering the formation of interconnecting self-assembled fibrillar networks (SAFIN) in supramolecular gelation.

The controlled preparation of organic nanotubesviaself-assembly of polycyclic aromatics is a contemporary challenge for supramolecular science. Here, we show that the self-assembly of pyrene-containing cationic amphiphiles, 3-(4-(pyren-6-yl)phenoxy)propan-1-ammonium salts (PyPA-Cl, PyPA-Br, and PyPA-SO44), can form high aspect ratio nanotubes with a uniform diameter distribution. We have also demonstrated that the counter anions also play an important role in the self-assembling results. The self-assembly of pyrene-containing cationic amphiphilic molecules with monovalent anions (Cl−− and Br−−) forms exclusively uniform nanotubes; whereas the self-assembly of amphiphiles with bivalent counter anions (SO42−) forms exclusively high aspect ratio nanoribbons. Furthermore, we have found that the diameter of the PyPA-Brnanotubes is larger than that of the PyPA-Clnanotubes. The research results reported herein represent an important step towards the preparation of functional nanostructures with controlled 1D architectures.

This communication describes the first example of the efficient use of a simple amphiphilic molecule as both a surfactant and an initiator in the miniemulsion polymerization of methyl methacrylate under AGET and ARGET ATRP conditions.

Propeller-shaped aromatic amphiphiles based on a conformationally flexible aromatic segment are shown to self-assemble into well-defined discrete nanostructures with high fluorescence characteristic.

4-Benzyloxy-4′-(2,3-dihydroxypropyloxy)biphenyls with lateral methyl substituents are a novel class of amphiphilic mesogens displaying thermotropic and lyotropic smectic and columnar mesophases due to microsegregation of hydrophilic regions from all-aromatic segments in the absence of a flexible alkyl chain.

A simple rapid solution-based method for forming the oxide layer at porous silicon is described which uses amphiphilic molecules to wet the hydrophobic porous structure.

1 H N.m.r. spectroscopy of mono- and disubstituted phenols and their ethers micellar solutions of anionic and cationic detergents reveals non-uniform upfield shifts of the different protons in the solubilisate; these shifts can be rationalised in terms of a preferred average orientation of the solubilisate in the micelle.