Thermoresponsive Carbohydrate-b-Polypeptoid Polymer Vesicles with Selective Solute Permeability and Permeable Factors for Solutes

Solute-permeable polymer vesicles are structural compartments for nanoreactors/nanofactories in the context of drug delivery and artificial cells. We previously proposed design guidelines for polymers that form solute-permeable vesicles, yet we did not provide enough experimental verification. In addition, the fact that there is no clear factor for identifying permeable solutes necessitates extensive trial and error. Herein, we report solute-permeable polymer vesicles based on an amphiphilic copolymer, thermoresponsive oligosaccharide-block-poly(N-n-propylglycine). The introduction of a thermoresponsive polymer as a hydrophobic segment into amphiphilic polymers is a viable approach to construct solute-permeable polymer vesicles. We also demonstrate that the polymer vesicles are preferentially permeable to cationic and neutral fluorophores and are hardly permeable to anionic fluorophores due to the electrostatic repulsion between the bilayer and anionic fluorophores. In addition, the permeability of neutral fluorophores increases with the increasing log P value of the fluorophores. Thus, the electrical charge and log P value are important factors for membrane permeability. These findings will help researchers develop advanced nanoreactors based on permeable vesicles for a broad range of fundamental and biomedical applications.

Polycaprolactone-Based Mimetic Antimicrobial Peptide Copolymers Vesicles as an Effective Drug-Carrier for Cancer Therapy

A novel series of amphiphilic mimicking antimicrobial peptide copolymers PCL16-b-Kn can assemble in water to form uniform vesicles. Transmission electron microscopy was used to observe the vesicular structure of the nanoparticles, and dynamic light scattering revealed their uniform size and narrow dispersion. Critical vesiculation concentrations were also tested, revealing that these vesicles can exist at low concentrations. Furthermore, in vitro and intracellular drug release of doxorubicin(DOX)-vesicles were conducted. These vesicles could encapsulate DOX and achieve efficient intracellular drug release. Overall, these copolymer vesicles exhibit potential application value as multifunctional drug-carrier systems with antibacterial capability in cancer therapy.

Sterical Recognition at Helix-Helix Interface of Leu-Aib-Based Polypeptides with and without a GxxxG-Motif

An amphiphilic polypeptide, poly(sarcosine)- b-(l-Leu-Aib)₈ (SL16), was reported to self-assemble into vesicles. A GxxxG motif, which is known to induce helix dimerization, is incorporated into the hydrophobic helical block of SL16 to synthesize poly(sarcosine)- b-(l-Leu-Aib)₂-(Gly-Aib-l-Leu-Aib-Gly-Aib)-(l-Leu-Aib)₃ (SG16). SG16 shows helix association in ethanol at a high concentration and low temperatures, which is not observed with SL16. SG16 self-assembles into vesicles, but are found to be more susceptible to rupture by the addition of Triton X-100 than SL16 vesicles. A mixture of SL16 and SG16 self-assembles into small sheets and micelles likely because of mismatch of the modes of helix association arising from sterical accommodation of iso-butyl groups at the helix-helix interface.

Self-assembly as a key player for materials nanoarchitectonics

The development of science and technology of advanced materials using nanoscale units can be conducted by a novel concept involving combination of nanotechnology methodology with various research disciplines, especially supramolecular chemistry. The novel concept is called 'nanoarchitectonics' where self-assembly processes are crucial in many cases involving a wide range of component materials. This review of self-assembly processes re-examines recent progress in materials nanoarchitectonics. It is composed of three main sections: (1) the first short section describes typical examples of self-assembly research to outline the matters discussed in this review; (2) the second section summarizes self-assemblies at interfaces from general viewpoints; and (3) the final section is focused on self-assembly processes at interfaces. The examples presented demonstrate the strikingly wide range of possibilities and future potential of self-assembly processes and their important contribution to materials nanoarchitectonics. The research examples described in this review cover variously structured objects including molecular machines, molecular receptors, molecular pliers, molecular rotors, nanoparticles, nanosheets, nanotubes, nanowires, nanoflakes, nanocubes, nanodisks, nanoring, block copolymers, hyperbranched polymers, supramolecular polymers, supramolecular gels, liquid crystals, Langmuir monolayers, Langmuir-Blodgett films, self-assembled monolayers, thin films, layer-by-layer structures, breath figure motif structures, two-dimensional molecular patterns, fullerene crystals, metal-organic frameworks, coordination polymers, coordination capsules, porous carbon spheres, mesoporous materials, polynuclear catalysts, DNA origamis, transmembrane channels, peptide conjugates, and vesicles, as well as functional materials for sensing, surface-enhanced Raman spectroscopy, photovoltaics, charge transport, excitation energy transfer, light-harvesting, photocatalysts, field effect transistors, logic gates, organic semiconductors, thin-film-based devices, drug delivery, cell culture, supramolecular differentiation, molecular recognition, molecular tuning, and hand-operating (hand-operated) nanotechnology.

Compartmentalized host spaces accommodating guest aromatic molecules in a chiral way in a helix-peptide-aromatic framework

A novel host molecular assembly of a free-standing flat nanosheet with compartmentalized spaces was prepared using a bolaamphiphilic peptide composed of two amphiphilic helical peptides and an oligo(naphthaleneethynylene) (ONE) unit at the center of the molecule. The nanosheet possesses void host spaces that can accommodate two mol-equivalent ONE groups to form columns of ONE groups in a right-handed helical way and ONE channels over a long distance. The present molecular system therefore can provide a chiral pore channel for relatively large molecules.

Phase-Separated Molecular Assembly of a Nanotube Composed of Amphiphilic Polypeptides Having a Helical Hydrophobic Block

Amphiphilic block polypeptides of poly(sarcosine)-b-(l- or d-Leu-Aib)₆ (SL12OMe or SD12OMe) and poly(sarcosine)-b-(l-Leu-Aib)₇ (SL14OMe) were reported to self-assemble into a nanotube morphology. Herein, we tried to construct a phase-separated nanotube by sticking two different kinds of nanotubes. SD12OMe nanotubes were found to stick to SL14OMe nanotubes with a heat treatment at 50 °C, but the sticking yield was limited. The amphiphilic polypeptides were functionalized by replacement of methyl ester with aromatic groups of N-ethylcarbazole (SL12Ecz) and naphthalimide (SD12NpiTEG), but they lost the ability to form homogeneous nanotubes. A fraction of the functionalized amphiphilic polypeptides mixing in the nanotube-forming amphiphilic polypeptides, a mixture of SL12OMe and SL12Ecz (9:1) as well as a mixture of SD12OMe and SD12NpiTEG (9:1), allowed nanotube formation. These two kinds of nanotubes partly stuck together with a heat treatment at 15 °C to maintain a segregated state of two kinds of aromatic groups along the nanotube, resulting in the formation of a phase-separated nanotube.

Immune responses against Lewis Y tumor-associated carbohydrate antigen displayed densely on self-assembling nanocarriers

Immune responses against Lewis Y (LY) displayed at varying densities on the nanocarriers were studied.

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.

Tuning the Viscoelasticity of Peptide Vesicles by Adjusting Hydrophobic Helical Blocks Comprising Amphiphilic Polypeptides

Amphiphilic block polypeptides of poly(sarcosine)-b-(l-Val-Aib)₆ and poly(sarcosine)-b-(l-Leu-Aib)₆ and their stereoisomers were self-assembled in water. Three kinds of binary systems of poly(sarcosine)-b-(l-Leu-Aib)₆ with poly(sarcosine)-b-poly(d-Leu-Aib)₆, poly(sarcosine)-b-poly(l-Val-Aib)₆, or poly(sarcosine)-b-(d-Val-Aib)₆ generated vesicles of ca. 200 nm diameter. The viscoelasticity of the vesicle membranes was evaluated by the nanoindentation method using AFM in water. The elasticity of the poly(sarcosine)-b-(l-Leu-Aib)₆/poly(sarcosine)-b-poly(d-Leu-Aib)₆ vesicle was 11-fold higher than that of the egg yolk liposome but decreased in combinations of the Leu- and Val-based amphiphilic polypeptides. The membrane elasticity is found to be adjustable by a suitable combination of helical blocks in terms of stereocomplex formation and the interdigitation of side chains among helices in the molecular assemblies.

Phase behaviors and self-assembled properties of ion-pairing amphiphile molecules formed by medium-chain fatty acids andl-arginine triggered by external conditions

The responsive self-assembled structures of ion-pairing amphiphile molecules will provide good insights into various fields.