Self-Assembly of Functional Protein Nanosheets from Thermoresponsive Bolaamphiphiles

Nanosheets are two-dimensional materials, less than 100 nm thick, that can be used for separations, biosensing, and biocatalysis. Nanosheets can be made from inorganic and organic materials such as graphene, polymers, and proteins. Here, we report the self-assembly of nanosheets under aqueous conditions from functional proteins. The nanosheets are synthesized from two fusion proteins held together by high-affinity interactions of two leucine zippers to form bolaamphiphiles. The hydrophobic domain, Z_R-ELP-Z_R, contains the thermoresponsive elastin-like peptide (ELP) flanked by arginine-rich leucine zippers (Z_R), each of which binds the hydrophilic fusion protein, globule-Z_E, via the glutamate-rich leucine zipper (Z_E) fused to a functional, globular protein. Nanosheets form when the proteins are mixed at 4 °C in aqueous solutions and then heated to 25 °C as the container is rotated end-over-end causing expansion and contraction of the air-water interface. The nanosheets are robust with respect to the choice of globular protein and can incorporate small fluorescent proteins that are less than 30 kDa as well as large enzymes, such as 80 kDa malate synthase G. Upon incorporation into nanosheets, enzymes retain more than 70% of their original activity, demonstrating the potential of protein nanosheets to be used for biosensing or biocatalytic applications.

Performance and selectivity of amphiphilic pillar[5]arene as stationary phase for capillary gas chromatography

Pillar[n]arenes possess highly symmetrical and rigid pillar-shaped architecture with π-electron rich cavity that afford their reliable host-guest recognition interactions towards matched guests. In this work, a novel amphiphilic pillar[5]arene (P5A-C10-2NH₂) was designed, synthesized and employed as the stationary phase for capillary gas chromatography. To date, they have not been reported in the field of chromatography. The P5A-C10-2NH₂ capillary column (10 m × 0.25 mm i.d.) was prepared by static coating method. Its capillary column exhibited moderate polarity and column efficiency of 2265 plates/m determined by naphthalene at 120 °C. As evidenced, the P5A-C10-2NH₂ column achieved advantageous separation performance for a mixture of 24 analytes of diverse types and exhibited different chromatographic selectivity from two pillar[5]arene derivatives columns and commercial HP-35 column with 35%-phenyl-methylpolysiloxane. Moreover, the P5A-C10-2NH₂ column baseline resolved more than a dozen positional and cis-trans isomers. Furthermore, the separation mechanism of P5A-C10-2NH₂ column was discussed by quantum chemical calculations. In addition, the P5A-C10-2NH₂ column had high thermal stability and excellent separation repeatability 0.01-0.04% for run-to-run, 0.03-0.17% for day-to-day and 3.2-3.9% for column-to-column. The special amphiphilic structure and high resolution for various analytes reveal the good potential of pillararenes as a new class of stationary phases for chromatographic analyses. Moreover, the TPG column achieved improved thermal stability over the GIL column and excellent repeatability.

Self-Assembling Peptidic Bolaamphiphiles for Biomimetic Applications

Bolaamphiphile, which is a class of amphiphilic molecules, has a unique structure of two hydrophilic head groups at the ends of the hydrophobic center. Peptidic bolaamphiphiles that employ peptides or amino acids as their hydrophilic groups exhibit unique biochemical activities when they self-organize into supramolecular structures, which are not observed in a single molecule. The self-assembled peptidic bolaamphiphiles hold considerable promise for imitating proteins with biochemical activities, such as specific affinity toward heterogeneous substances, a catalytic activity similar to a metalloenzyme, physicochemical activity from harmonized amino acid segments, and the capability to encapsulate genes like a viral vector. These diverse activities give rise to large research interest in biomaterials engineering, along with the synthesis and characterization of the assembled structures. This review aims to address the recent progress in the applications of peptidic bolaamphiphile assemblies whose densely packed peptide motifs on their surface and their stacked hydrophobic centers exhibit unique protein-like activity and designer functionality, respectively.

Amphipathic design dictates self-assembly, cytotoxicity and cell uptake of arginine-rich surfactant-like peptides

Amphiphilicity is the most critical parameter in the self-assembly of surfactant-like peptides (SLPs), regulating the way by which hydrophobic attraction holds peptides together. Its effects go beyond supramolecular assembly and may also trigger different cell responses of bioactive peptide-based nanostructures. Herein, we investigate the self-assembly and cellular effects of nanostructures based on isomeric SLPs composed by arginine (R) and phenylalanine (F). Two amphipathic designs were studied: a diblock construct F4R4 and its bolaamphiphile analog R2F4R2. A strong sequence-dependent polymorphism emerges with appearance of globules and vesicle-like assemblies, or flat nanotapes and cylindrical micelles. The diblock construct possesses good cell penetrating capabilities and effectiveness to kill SK-MEL-28 melanoma tumor cells, in contrast to reduced intracellular uptake and low cytotoxicity exhibited by the bolaamphiphilic form. Our findings demonstrate that amphipathic design is a relevant variable for self-assembling SLPs to modulate different cellular responses and may assist in optimizing the production of nanostructures based on arginine-enriched sequences in cell penetrating and antimicrobial peptides.

Synergistic effect of hydrophobic and hydrogen bonding interaction-driven viologen-pyranine charge-transfer aggregates: adenosine monophosphate recognition

Understanding the role of non-covalent interactions that dictate and fine-tune the direction of self-assembly of functional molecules is crucial for developing stimuli responsive materials. Herein, we systematically designed and synthesized viologen derivatives with hydrophobic dodecyl chains and alkyl carboxylic acid functionalities. The complementary electronic and electrostatic counterpart of viologens was chosen as pyranine. Viologens comprising of a hydrophobic dodecyl chain on one terminal and hydrogen bonding alkyl carboxylic acid on the other (V1 and V2) underwent aggregation to a varying extent upon interaction with pyranine. The length of the alkyl carboxylic acid had a greater impact on the nature and morphology of the aggregates. Control molecules (V3 and V4) in which 4,4'-bipyridine was symmetrically quaternized with alkyl carboxylic acids did not aggregate upon interaction with pyranine. The delicate balance existing between the hydrophobicity of the dodecyl chains and the intermolecular hydrogen bonding interaction between the alkyl carboxylic acid groups in V1 or V2 of the corresponding charge transfer (CT) complexes was instrumental in driving the aggregation. The CT aggregates of [V1-Pyr] and [V2-Pyr] exhibited excellent stability in water which disaggregated at physiological pH. We emphasize on the importance of synergy between hydrophobic and hydrogen bonding interactions in reinforcing each other to drive the supramolecular aggregation of the CT complexes. Such pH dependent CT aggregates are of importance as scaffolds in pH controlled drug release. In the present study, the CT aggregates were evaluated for adenosine nucleotide recognition in water; [V1-Pyr] and [V2-Pyr] exhibited selective response towards adenosine monophosphate via deprotonation induced dissolution of aggregates in water leading to emission enhancement.

Synthesis of lactobionic acid based bola-amphiphiles and its application as nano-carrier for curcumin delivery to cancer cell cultures in-vitro

Curcumin is highly effective against various types of cancers; however, its low aqueous solubility, high metabolism and non-specificity hinder its efficacy. This study reports the synthesis of three lactobionic acid containing bola-amphiphiles and their investigation for curcumin nano-vesicular delivery into cancer cells. Synthesized bola-amphiphiles were capable of forming nano-vesicles and curcumin loading in a lipophilicity dependent manner. Bola-amphiphile with higher lipophilicity (C12) caused 89.55 ± 5.52% drug encapsulation in its spherical shape nano-vesicles (195.90 ± 0.83 nm). Bola-amphiphile resulting increased curcumin encapsulation with minimum vesicles size was further investigated for cellular uptake and in-vitro anticancer activity. Anticancer activity of curcumin significantly increased against the tested cancer cells upon loading in bola-amphiphile nano-vesicles. Furthermore, nano-vesicular drug delivery of curcumin enhanced its cellular uptake even at the lowest concentration of 1.25 µg/mL.It is concluded that the synthesized bola-amphiphile based nano-vesicles can efficiently deliver curcumin to the tested cancer cells and needs to be tested for established anticancer drugs against different cancer cell lines for effective treatment of cancer.

Controlled synthesis of organic two-dimensional nanostructures via reaction-driven, cooperative supramolecular polymerization

The bottom-up approach of supramolecular polymerization is an effective synthetic method for functional organic nanostructures. However, the uncontrolled growth and polydisperse structural outcome often lead to low functional efficiency. Thus, precise control over the structural characteristics of supramolecular polymers is the current scientific hurdle. Research so far has tended to focus on systems with inherent kinetic control by the presence of metastable state monomers either through conformational molecular design or by exploring pathway complexity. The need of the hour is to create generic strategies for dormant states of monomers that can be extended to different molecules and various structural organizations and dimensions. Here we venture to demonstrate chemical reaction-driven cooperative supramolecular polymerization as an alternative strategy for the controlled synthesis of organic two-dimensional nanostructures. In our approach, the dynamic imine bond is exploited to convert a non-assembling dormant monomer to an activated amphiphilic structure in a kinetically controlled manner. The chemical reaction governed retarded nucleation-elongation growth provides control over dispersity and size.

Fluorescent supramolecular polymers with aggregation induced emission properties

This review summarizes the recent developments in AIE fluorescent supramolecular polymeric materials based on different types of intermolecular noncovalent interactions, and their wide ranging applications as chemical sensors, organic electronic materials, bio-imaging agents and so on.

Supramolecular self-assemblies for bacterial cell agglutination driven by directional charge-transfer interactions

Two supramolecular amphiphiles are fabricated through directional charge-transfer interactions, which self-assemble into nanofibers and nanoribbons. Due to the existence of galactose on their surface, these self-assemblies act as a cell glue to agglutinate E. coli, benefiting from multivalent interactions.

The sensitivity of donor - acceptor charge transfer to molecular geometry in DAN - NDI based supramolecular flower-like self-assemblies

A charge-transfer (CT) complex self-assembled from an electron acceptor (NDI-EA: naphthalene diimide with appended diamine) and an electron donor (DAN: phosphonic acid-appended dialkoxynapthalene) in aqueous medium. The aromatic core of the NDI and the structure of DAN1 were designed to optimize the dispersive interactions (π-π and van der Waals interactions) in the DAN1–NDI-EA self-assembly, while the amino groups of NDI also interact with the phosphonic acid of DAN1 via electrostatic forces. This arrangement prevented crystallization and favored the directional growth of 3D flower nanostructures. This molecular geometry that is necessary for charge transfer to occur was further evidenced by using a mismatching DAN2 structure. The flower-shaped assembly was visualized by scanning electron and transmission electron microscopy. The formation of the CT complex was determined by UV-vis and cyclic voltammetry and the photoinduced electron transfer to produce the radical ion pair was examined by femtosecond laser transient absorption spectroscopic measurements.

p-Sulfonatocalix[6]arene-dodecyltrimethylammonium Supramolecular Amphiphilic System: Relationship between Calixarene and Micelle Concentration

In this work, the formation of supramolecular mixed micelles from a hexamethylated p-sulfonatocalix[6]arene (SC6HM) derivative and a conventional cationic surfactant (dodecyltrimethylammonium bromide, C₁₂TAB) was investigated by surface tension and using pyrene as a micropolarity fluorescent probe to gain insights into the role of the calixarene concentration on the aggregation behavior. The formation of micelles at a concentration well below the critical micelle concentration of pure surfactant was observed in the presence of very low concentrations of SC6HM (below the micromolar range). Interestingly, the critical micelle concentration of the mixed system was shown to be rather insensitive to the concentration of SC6HM. On the other hand, the concentration of mixed micellar aggregates was demonstrated to be highly dependent on the macrocycle concentration and less dependent on the C₁₂TAB concentration in the range between the critical micelle concentrations of the mixed systems and pure surfactant.

Fluorescent Supramolecular Polymeric Materials

Fluorescent supramolecular polymeric materials are rising stars in the field of fluorescent materials not only because of the inherent optoelectronic properties originating from their chromophores, but also due to the fascinating stimuli-responsiveness and reversibility coming from their noncovalent connections. Especially, these noncovalent connections influence the fluorescence properties of the chromophores because their state of aggregation and energy transfer can be regulated by the assembly-disassembly process. Considering these unique properties, fluorescent supramolecular polymeric materials have facilitated the evolution of new materials useful for applications in fluorescent sensors, probes, as imaging agents in biological systems, light-emitting diodes, and organic electronic devices. In this Review, fluorescent supramolecular polymeric materials are classified depending on the types of main driving forces for supramolecular polymerization, including multiple hydrogen bonding, electrostatic interactions, π-π stacking interactions, metal-coordination, van der Waals interactions and host-guest interactions. Through the summary of the studies about fluorescent supramolecular polymeric materials, the status quo of this research field is assessed. Based on existing challenges, directions for the future development of this field are furnished.

Preparation and evaluation of a novel anticancer drug delivery carrier for 5-Fluorouracil using synthetic bola-amphiphile based on lysine as polar heads

A novel bolaamphiphile surfactant N,N'-(dodecane-1, 12-diyl) bis (2,6-diaminohexanamide) (DADL) was designed and synthesized using l-lysine and 1,12-diaminododecane as the hydrophilic and hydrophobic part, respectively. After separation and purification, the structure of the synthetic bolaamphiphile surfactant was verified by FTIR, MS and ¹H NMR. The synthetic bolaamphiphile was able to self-assemble to form vesicles. After formulation screening, vesicles loaded with 5-Fluorouracil (5-Fu) were prepared with Tween 60 and DADL by sonication and were examined by dynamic light scattering and transmission electron microscopy. Micro-FTIR was applied to investigate the conformation of the bola molecules within the vesicle membrane. The release profile of the vesicles showed a pH-sensitive and sustained release. No significant toxicity was observed in an in vitro cell viability assay. The antitumor efficacy of the 5-Fu-loaded vesicles on H₂₂ tumor-bearing mice was remarkably high due to the EPR effects. These results show that our novel bolaamphiphile derived from lysine has excellent potential as a pH-sensitive drug carrier.

β-Cyclodextrin induced hierarchical self-assembly of a cationic surfactant bearing an adamantane end group in aqueous solution

A cationic surfactant with adamantane as the end group, 1-[11-((adamantane-1-carbonyl)oxy)-undecyl]pyridinium bromide (AP), has been synthesized. Its β-cyclodextrin (β-CD) induced hierarchical self-assembling behaviors in aqueous solution were investigated using transmission or scanning electron microscopy methods and small-angle X-ray scattering measurements. Like conventional single chain surfactants, micelles could be formed by AP itself in dilute solutions. However, the dramatic phase transitions of these micelles occurred when host-guest inclusions between AP and β-CD were sequentially produced at different host/guest molar ratios (R), corresponding to the supramolecules with different chemical structures. The AP micelles could be changed into spherical unilamellar vesicles by adding β-CD to reach an R value of 1 : 1. Such vesicles then evolved into multi-wall nanotubes or hydrogels when the β-CD amount was further increased to obtain an R value of 2 : 1. The unique structural characteristics of these supramolecular aggregates come from their "monolayer-like" walls, which have rarely been reported in the past for CD/surfactant inclusion complexes. The interesting results obtained here not only enrich the β-CD/surfactant aggregation systems, but also provide a novel and facile strategy to tune the morphology and structure of aggregates.

Structural and Thermal Behavior of Meglumine-Based Supra-Amphiphiles in Bulk and Assembled in Water

Supra-amphiphiles are a new class of building blocks that are fabricated by means of noncovalent forces. In this work, we studied the formation of supra-amphiphiles by combining hydrophilic meglumine (MEG) with hydrophobic maleated castor oils (MACO). Spectroscopic analysis demonstrated that ionic interactions are the main driving force in the fabrication of these materials. Subsequently, supra-amphiphile/water systems were examined for their structure and water behavior by polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and differential scanning calorimetry (DSC). Micellar and lamellar liquid crystalline phases were observed. Finally, we observed that the supra-amphiphiles produced using an excess of MEG retain a large amount of water. As bound water plays an important role in biointerfacial interactions, we anticipate that these materials will display a pronounced potential for biomedical applications.

First report of charge-transfer induced heat-set hydrogel. Structural insights and remarkable properties

The remarkable ability of a charge-transfer (CT) complex prepared from a pyrene-based donor (Py-D) and a naphthalenediimide-based acceptor (NDI-A) led to the formation of a deep-violet in color, transparent hydrogel at room temperature (RT-gel). Simultaneously, the RT-gel was diluted beyond its critical gelator concentration (CGC) to obtain a transparent sol. Very interestingly, the resultant sol, on heating above 70 °C, transformed into a heat-set gel instantaneously with a hitherto unknown CGC value. Detailed studies revealed the smaller globular aggregates of the RT-gels fuse to form giant globules upon heating, which, in turn, resulted in heat-set gelation through further aggregation. The thermoresponsive property of Py-D alone and 1 : 1 Py-D : NDI-A CT complex was investigated in detail which revealed the hydrophobic collapse of the oxyethylene chains of the CT complex upon heating was mainly responsible for heat-set gelation. Thixotropy, injectability, as well as stimuli responsiveness of the RT-gels were also addressed. In contrast, heat-set gel did not show thixotropic behavior. The X-ray diffraction (XRD) patterns of the xerogel depicted lamellar packing of the CT stacks in the gel phase. Single crystal XRD studies further evidenced the 1 : 1 mixed CT stack formation in the lamellae and also ruled out orthogonal hydrogen bonding possibilities among the hydrazide unit in the CT gel although such interaction was observed in a single crystal of NDI-A alone. In addition, a Ag(+)-ion triggered metallogelation of NDI-A and nematic liquid-crystalline property of Py-D were also observed.

Reversible morphological changes of assembled supramolecular amphiphiles triggered by pH-modulated host–guest interactions

Acid–base modulated host–guest binding at the micellar–water interface triggers reversible oblate ellipsoid-to-lamellar morphological transitions revealing the relationship between and morphology.

Self-assembly of fluorescent diimidazolium salts: tailor properties of the aggregates changing alkyl chain features

Self assembly of fluorescent diimidazolium NDI salts showed properties of aggregates changing with alkyl chain length, with an odd–even effect.

Pillar[10]arene-based host–guest complexation promoted self-assembly: from nanoparticles to uniform giant vesicles

A novel host-guest recognition motif between a water-soluble pillar[10]arene and pyrene derivative was established and further applied in the fabrication of a pH-responsive supra-amphiphile.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

Redox-Responsive Amphiphilic Macromolecular [2]Pseudorotaxane Constructed from a Water-Soluble Pillar[5]arene and a Paraquat-Containing Homopolymer

Here we report a redox-responsive host-guest complex between a new water-soluble pillar[5]arene (WP5) and a paraquat derivative. Compared with the neutral form of the paraquat derivative that binds WP5 weakly, its dication form binds WP5 much more strongly. Furthermore, we utilize this new water-soluble redox-responsive molecular recognition motif to construct the first pillararene-based amphiphilic macromolecular [2]pseudorotaxane, which self-assembles into redox-responsive polymeric vesicles in water. Such pillararene-based supramolecular vesicles were further used to construct a drug delivery system to encapsulate and controlled release DOX·HCl, an anticancer drug. The uptake of these DOX·HCl-loaded supramolecular vesicles by cancer cells was studied with confocal laser scanning microscopy. Meanwhile, DOX·HCl-loaded supramolecular vesicles showed anticancer activity in vitro comparable to free DOX·HCl under the examined conditions.

Charge-Transfer Supra-Amphiphiles Built by Water-Soluble Tetrathiafulvalenes and Viologen-Containing Amphiphiles: Supramolecular Nanoassemblies with Modifiable Dimensions

In this study, multidimensional nanoassemblies with various morphologies such as nanosheets, nanorods, and nanofibers are developed via charge-transfer interaction and supra-amphiphile self-assembling in aqueous phase. The charge-transfer interactions between tetrathiafulvalene derivatives (TTFs) and methyl viologen derivatives (MVs) have been confirmed by the characteristic charger-transfer absorption. (1) H NMR and electrospray ionizsation mass spectrometry (ESI-MS) analyses also indicate supra-amphiphiles are formed by the combination of TTFs and MVs head group through charge-transfer interaction and Coulombic force. X-ray single crystal structural studies, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) reveal that both linkage pattern of TTFs in hydrophilic part and alkane chain structure in hydrophobic part have significant influence on nanoassemblies morphology and microstructure. Moreover, gold nanoparticles (AuNPs) are introduced in the above supramolecular nanoassemblies to construct a supra-amphiphile-driven organic-AuNPs assembly system. AuNPs could be assembled into 1D-3D structures by adding different amount of MVs.

Ordered liquids and hydrogels from alkenyl succinic ester terminated bola-amphiphiles for large-scale applications

The present study describes an economic and scalable approach to aqueous mesophases from bola-amphiphiles (BA) obtained via nucleophilic addition of dimer fatty acid based α,ω-polyesterdiols (PES) on cyclic acid anhydrides and conversion of the carboxylic end groups into ammonium salts. Novel bola-amphiphilic head groups are introduced using alkenyl succinic anhydrides (ASA). The additional terminal hydrophobic side chains favour the self-assembly of polymeric BA of different molecular weights into nanoscale anisotropic objects, their shape and ordering into nematic or lamellar-like phases being dependent on the length and structural uniformity of the ASA chains. Corresponding diester based on C15 (hydrogenated bisphenol-A, HBA) and C8 (1,4-cyclohexanedimethanol, CHDM) spacers have been prepared and the self-assembly of the resulting BA in water has been studied using SAXS, (2)H-NMR and optical polarization microscopy. While the rigid C8 spacer impedes any ordering, ASA capped C15 tends to form ordered hydrogels over extended regions of the phase diagram that resemble mesh phases and L(α)/L(3) polymorphism. Rheological and simulation results confirm the presence of elastically responding bicontinuous morphologies and biased porous assemblies resembling interconnected mesh phases. Both the use of the dimer fatty acid based spacer as well as of ASA head groups open up large-scale applications of ordered liquids (or hydrogels) as a formulation basis for e.g. films, coatings and adhesives.

Supra-amphiphilic aggregates formed by p-sulfonatocalix[4]arenes and the antipsychotic drug chlorpromazine

We report here a supramolecular strategy to directly assemble the small molecular antipsychotic drug chlorpromazine (CPZ) into nanostructures, induced by p-sulfonatocalix[4]arene (SC4A) and p-sulfonatocalix[4]arene tetraheptyl ether (SC4AH), with high drug loading efficiencies of 61% and 46%, respectively. The binary host-guest assembly process was monitored using optical transmittance measurements, and the size and morphology of these two kinds of supra-amphiphilic assemblies were identified using a combination of light scattering and high-resolution transmission electron microscopy, which showed solid spherical micelles. This strategy presents new opportunities for the development of high loading drug-containing carriers with easy processability for drug delivery.

Mono-molecule-layer nano-ribbons formed by self-assembly of bolaamphiphiles

Amphiphilic molecules generally tend to organize spontaneously into spherical or cylindrical micelles/vesicles in appropriate liquid media and conditions, and seldom form two dimensional (2D) planar structures with a regular shape, due to their energetically unfavorable state. Herein, the self-assembly of a new bolaamphiphile bearing a bistriazole-pyrene unit leads to the formation of mono-molecule-layer nano-ribbons. The π-π stacking interaction between the rigid bistriazole-pyrene units and electrostatic screening contributed by the aromatic counterion tosyl groups are responsible for the 2D alignment of the molecules in the aggregate. Partial replacement of the tosyl groups causes a reduction in the width of the nano-ribbons and the coordination of triazole with Pd2+ ions results in the collapse of the self-assembled structure. This study supplies new clues for fabricating molecular level 2D nanostructures by bottom-up supramolecular assembly.

Dual responsive supramolecular amphiphiles: guest molecules dictate the architecture of pyridinium-tailored anthracene assemblies

By introducing an electron-deficient guest molecule and a counter anion, the assembly morphology of 1-[11-(2-anthracenylmethoxy)-11-oxoundecyl]pyridinium bromide (2-AP) was transformed to microsheets and nanofibers from microtubes, respectively.

An enzyme-responsive supra-amphiphile constructed by pillar[5]arene/acetylcholine molecular recognition

A novel molecular recognition motif between a water-soluble pillar[5]arene (WP5) and acetylcholine is established with an association constant of (5.05 ± 0.13) × 10⁴ M⁻¹.

Carbon nanotube/biocompatible bola-amphiphile supramolecular biohybrid materials: preparation and their application in bacterial cell agglutination

Supramolecular biohybrid materials were successfully constructed driven by non-covalent interactions between three biocompatible bolaform amphiphiles and single walled carbon nanotubes (SWNTs). The existence of galactoses in these supramolecular systems endowed the hybrid materials with interesting bio-function. By introducing the SWNTs as semi-flexible platforms, these supramolecular biohybrid materials display excellent agglutination ability for E. coli.

Copper(II) ion selective and strong acid-tolerable hydrogels formed by an L-histidine ester terminated bolaamphiphile: from single molecular thick nanofibers to single-wall nanotubes

An L-histidine ester terminated bolaamphiphile (BolaHis) was found to form hydrogels and self-assemble into single-wall nanotubes and single molecular thick fibers triggered by proton and copper ions, respectively. The hydrogels showed good tolerance to a concentrated acid environment and excellent selectivity towards Cu(2+) over other metal ions.

Supramolecular glycolipid based on host-enhanced charge transfer interaction

Supramolecular glycolipid has been fabricated based on ternary complex system, which is composed of naphthyl glucosamine (GlcNap), alkyl viologen (RV8), and cucurbit[8]uril (CB[8]). CB[8] plays a key role to connect the other two building blocks together, and the process is driven by host-enhanced charge transfer interaction. Compared with the classic glycolipids, supramolecular glycolipids display redox responsiveness. Supramolecular glycolipids are able to self-assemble in water to form spherical aggregations, such as vesicle like structure. In addition, spherical aggregations can specifically interact with Concanavalin A, indicating that the carbohydrate groups are available on the surfaces of the aggregates.

Hierarchical self-assembly: well-defined supramolecular nanostructures and metallohydrogels via amphiphilic discrete organoplatinum(II) metallacycles

Metallacyclic cores provide a scaffold upon which pendant functionalities can be organized to direct the formation of dimensionally controllable nanostructures. Because of the modularity of coordination-driven self-assembly, the properties of a given supramolecular core can be readily tuned, which has a significant effect on the resulting nanostructured material. Herein we report the efficient preparation of two amphiphilic rhomboids that can subsequently order into 0D micelles, 1D nanofibers, or 2D nanoribbons. This structural diversity is enforced by three parameters: the nature of the hydrophilic moieties decorating the parent rhomboids, the concentration of precursors during self-assembly, and the reaction duration. These nanoscopic constructs further interact to generate metallohydrogels at high concentrations, driven by intermolecular hydrophobic and π-π interactions, demonstrating the utility of coordination-driven self-assembly as a first-order structural element for the hierarchical design of functional soft materials.