The Introduction of π-π Stacking Moieties for Fabricating Stable Micellar Structure: Formation and Dynamics of Disklike Micelles

Pyridine-appended disulfidephospholipids enable exceptionally high drug loading and stability as a robust liposomal platform

Low drug loading and instability of liposomes are two main challenges in the clinic. Herein, a liposomal platform from alternative pyridine-appended disulfidephospholipid (Pyr-SS-PC) was developed for delivering camptothecin (CPT) with high loading and stability. These Pyr-SS-PC lipids with π-π stacking open a general gate in the delivery of aromatic ring-containing drugs.

Ionic surfactants as assembly crosslinkers triggered supramolecular membrane with 2D↔3D conversion under multiple stimulus

HYPOTHESIS

General strategies leading to 2D assemblies promise a significant step forward in the development of supramolecular materials with diversity and superiority. Considering molecular packing parameter indicates a connection between molecular geometry and aggregate morphology, we predict the introduction of ionic surfactants as assembly crosslinker would be endowed to develop a methodology of 2D supramolecular assembles.

EXPERIMENTS

In this work, by introducing ionic surfactants such as sodium dodecylsulfate (SDS), the molecular packing parameter P in bolaamphiphile (A2G) system was increased, which successfully manipulated the transformation of the 3D vesicles into 2D membranes. This 2D membranes further showed excellent light and enzyme response, and thus 2D to 3D morphological conversion can be rationally controlled via UV/Vis light irradiation and alternate addition of β-CD and α-amylase. Significantly, the 2D feature revealed not only a remarkable fluorescence enhancement to luminescent molecules but also the ability to effectively remove pollutants from water through filtration.

FINDINGS

We report a general and facile strategy for the construction of 2D supramolecular membranes, initiated by introducing ionic surfactants as assembly crosslinker to increase P. In the existence of stimulus response factors, 2D↔3D morphological conversion can be further controlled in a flexible manner, which opens up a new paradigm leading to interconvertible supramolecular materials.

Toward Highly Robust Nonvolatile Multilevel Memory by Fine Tuning of the Nanostructural Crystalline Solid-State Order

Organic resistive memory (ORM) offers great promise for next-generation high-density multilevel-cell (MLC) data storage. However, the fine tuning of crystalline order among its active layer still remains challenging, which largely restricts ORM behavior. Here, an exceptional solid-state transition from disordered orientations to highly-uniform orientation within the ORM layer is facilely triggered via molecular strategic tailoring. Two diketopyrrolopyrrole-based small molecular analogues (NI₁ TDPP and NI₂ TDPP) are demonstrated to display different symmetry. The asymmetric NI₁ TDPP shows an irregular solid-state texture, while the centro-symmetric NI₂ TDPP conforms to an ordered out-of-plane single-crystalline pattern that aligns with the foremost charge transportation along the substrate normal, and exhibits excellent MLC memory characteristics. Moreover, this highly oriented pattern guarantees the large-area film uniformity, leading to the twofold increase in the yield of as-fabricated ORM devices. This study reveals that the solid-state crystalline nanostructural order of organic materials can be controlled by reasonable molecular design to actuate high-performance organic electronic circuits.

Dimethyl Sulfoxide-Free and Water-Soluble Fluorescent Probe for Detection of Bovine Serum Albumin Prepared by Ionic Co-assembly of Amphiphiles

Detection of bovine serum albumin (BSA) is an important issue in the sense of medical applications and enzymatic reactions; however, the recently developed fluorescent probes require the involvement of dimethyl sulfoxide (DMSO), which may be detrimental to proteins. In this study, we demonstrated a DMSO-free and water-soluble fluorescent probe prepared by ionic co-assembly of amphiphiles. The cationic amphiphile is a newly designed molecule (denoted by DPP-12) bearing a conjugated diketopyrrolopyrrole (DPP) and two tetraphenylethylene groups. It turns out that the fluorescence emission of DPP-12 depends on the amount of anionic amphiphilic sodium dodecyl benzene sulfonate (SDBS). The fluorescence intensity first increases and then decreases with the concentration of SDBS, and each branch presents a linear relationship. BSA consumes SDBS by the formation of complexes, thus leading to an increase of fluorescence intensity of the mixed solution of DPP-12 and SDBS. Therefore, the mixed solution of DPP-12 and SDBS was applied as a fluorescent probe to detect the low concentration of BSA by back-titration. This fluorescent probe does not require DMSO and has good tolerance to metal ions in blood and good photostability. The limit of detection is as low as 940 nM, almost 3 orders of magnitude lower than the content in organisms.

Light-Responsive Polymeric Micellar Nanoparticles with Enhanced Formulation Stability

Light-sensitive polymeric micelles have recently emerged as promising drug delivery systems for spatiotemporally controlled release of payload at target sites. Here, we developed diazonaphthoquinone (DNQ)-conjugated micellar nanoparticles that showed a change in polarity of the micellar core from hydrophobic to hydrophilic under UV light, releasing the encapsulated anti-cancer drug, doxetaxel (DTX). The micelles exhibited a low critical micelle concentration and high stability in the presence of bovine serum albumin (BSA) solution due to the hydrophobic and π–π stacking interactions in the micellar core. Cell studies showed enhanced cytotoxicity of DTX-loaded micellar nanoparticles upon irradiation. The enhanced stability would increase the circulation time of the micellar nanoparticles in blood, and enhance the therapeutic effectiveness for cancer therapy.

Synthesis and self-assembly of amphiphilic precision glycomacromolecules

Amphiphilic precision glycomacromolecules (APG) are synthesized using solid-phase synthesis and studied for their self-assembly behavior and as inhibitors of bacterial adhesion.

Synthesis of MOF525/PEDOT Composites as Microelectrodes for Electrochemical Sensing of Dopamine

Dopamine (DA) is an important neurotransmitter responsible for the functions and activities of multiple systems in human. Electrochemical detection of DA has the advantages of fast analysis and cost-effectiveness, while a regular electrode probe is restricted to laboratory use because the probe size is too large to be suitable for an in vivo or in vitro analysis. In this study, we have developed porphyrin-based metal organic framework (MOF525) and poly(3,4-ethylenedioxythiophene) (PEDOT)-based composites to modify microelectrode for DA detection. Two types of PEDOT monomers with different functional groups were investigated in this study. By varying the monomer ratios, electrolyte concentrations, and electropolymerization temperature, it was found that the PEDOT monomer containing carboxylic group facilitated the formation of regular morphology during the electropolymerization process. The uniform morphology of the PEDOT promoted the electron transmission efficiency in the same direction, while the MOF525 provided a large reactive surface area for electrocatalysis of DA. Thus, the MOF525/PEDOT composite improved the sensitivity-to-noise ratio of DA signaling, where the sensitivity reached 11 nA/μM in a good linear range of 4–100 µM. In addition, porphyrin-based MOF could also increase the selectivity to DA against other common clinical interferences, such as ascorbic acid and uric acid. The as-synthesized microelectrode modified with MOF525/PEDOT in this study exhibited great potential in real time analysis.

Gemini-Type Supramolecular Amphiphile Based on a Water-Soluble Pillar[5]arene and an Azastilbene Guest and Its Application in Stimuli-Responsive Self-Assemblies

Supramolecular amphiphiles are a type of intriguing building blocks to fabricate self-assembled nanostructures that can be applied in diverse fields. Gemini-type supramolecular amphiphiles, containing two hydrophobic tails and two hydrophilic head groups linked by a spacer, are good candidates to fabricate many advanced materials that are able to apply in surface modification, drug/gene delivery, and solubilization. Pillararenes, the fifth generation of macrocyclic host molecules, have been used to fabricate many supramolecular amphiphiles that played important roles in biomedical fields and materials science. However, compared with single-chain and bola-type supramolecular amphiphiles, the studies of gemini-type supramolecular amphiphiles based on pillararenes are very rare. Herein, a new strategy to prepare gemini-type supramolecular amphiphiles was reported. A new acid-responsive host?guest recognition motif in water on the basis of a 4,4?-azastilbene derivative (G1) and a water-soluble pillar[5]arene (WP5) was fabricated. The gemini-type supramolecular amphiphile was constructed by an azastilbene amphiphilic guest (G2) and WP5. Then its application in stimuli-responsive self-assemblies was investigated. G2 self-assembled into nanoribbons in water. Upon addition of WP5, the gemini-type supramolecular amphiphile formed, leading to the formation of disklike micelles. After further addition of hydrochloric acid, the morphology changed into nanosheets.

The π-π stacking-guided supramolecular self-assembly of nanomedicine for effective delivery of antineoplastic therapies

In traditional nano drug-delivery systems, the complex chemical bonds between drug and carrier often complicate the preparation process and are less prone to rupture upon entry into the target, which is detrimental to the timely release of the drug. The π-π stacking provides us with a promising alternative as it is a weak interaction between the aromatic rings. Since most antitumor drugs are hydrophobic molecules with complex aromatic π-π-conjugated structures, the construction of self-assembly based on π-π stacking between drugs and carriers has the advantage of improving the stability and drug loading capacity as well as the improvement of hydrophilicity and biosafety. This article introduces the recent advances in π-π stacking-guided nano self-assembly for antineoplastic delivery.

Self-Assembly and Functions of Star-Shaped Oligomeric Surfactants

Oligomeric surfactants consist of three or more amphiphilic moieties which are connected by spacer groups covalently at the level of headgroups. It provides a possible route to bridge the gap from conventional single-chain surfactants to polymeric surfactants and leads to many profound improvements in the properties of surfactants in aqueous solution and at the air/water and water/solid interfaces. Generally, oligomeric surfactants are categorized into linear, ring-like, and star-shaped on the basis of the topological structures of their spacer groups, and their aggregation behavior strongly depends on the resultant topological structures. In recent years, we studied trimeric, tetrameric, and hexameric surfactants with a star-shaped spacer which spreads from a central site of elemental nitrogen or carbon, and their charged headgroups connect with each other through the spacers. It has been found that both the nature of spacer groups and the degree of oligomerization show important influences on the self-assembly of oligomeric surfactants and provide great possibilities in fabricating various surfactant aggregate morphologies by adjusting the molecule conformations. The unique self-assembly behavior endows them with superior physicochemical properties and potential applications. This feature article summarizes the development of star-shaped oligomeric surfactants, including self-assembly at the air/water and water/solid interfaces, self-assembly in aqueous solution, and their functions. We expect that this review could provide a comprehensive understanding of the structure-property relationship and various potential applications of star-shaped oligomeric surfactants and offer additional motivation for their future research.

Photocontrolled Coumarin-diphenylalanine/Cyclodextrin Cross-Linking of 1D Nanofibers to 2D Thin Films

Using coumarin-modified diphenylalanine (CO-FF) and γ-cyclodextrin (γ-CD) as building blocks, we successfully constructed one-dimensional nanofibers with several nanometers in width and tens of micrometers in length. Through the photodimerization of coumarin units in CO-FF⊂γ-CD complexes, the resultant nanofibers could be cross-linked to organic 2D thin films with a lateral dimension of tens of micrometers and a thickness of nanometers. The resultant thin films exhibited a significant fluorescence enhancement for twisted intramolecular charge-transfer (TICT) molecules and effective removal of pollutant from water through filtration. This 1D → 2D morphological conversion controlled by light may provide a novel strategy to construct the highly ordered nanostructures that can be used as templates for making nanoscaled materials with defined sizes and shapes.

Novel morphologies of poly(allyamine hydrochloride)-methotrexate nanoassemblies for methotrexate delivery

Poly(allylamine hydrochloride)-methotrexate (PAH-MTX) nanoassemblies with novel morphologies (i.e. nanostrips, nanorolls, nanosheets, and nanospheres) were achieved for the first time via supramolecular self-assembly directed by the synergistic action of various non-covalent interactions between PAH and MTX molecules in aqueous solution. Herein, MTX acted in a versatile manner as both a morphology-regulating agent and a small molecular hydrophobic anticancer drug. Moreover, different morphologies presented diverse drug release profiles, which may be caused by the distinctive interactions between PAH and MTX molecules. Synergistically non-covalent interactions, including electrostatic interactions, van der Waals forces, and hydrogen bonding, favored easier matrix corrosion and more rapid drug release of non-spherical structures (i.e. nanostrips, nanorolls, and nanosheets) through the ligand exchange process. On the other hand, the highly sealed encapsulation mode for hydrophobic MTX molecules made the nanospheres exhibit slower and better controlled release. In addition, in vitro bioassay tests showed that nanostrips displayed the most obvious suppression on the viability of cancer cells among other morphologies, especially after a longer duration. The strategy of using small molecular anticancer drugs not as passively delivered cargoes but as effective molecular building blocks, opens up a new way to develop self-delivering drugs for anticancer therapy.

Self-assembly of two-dimensional structures in water from rigid and curved amphiphiles with a low molecular weight

Rigid and curved amphiphiles with very low molecular weight (MW < 500 Da) self-assemble into two-dimensional structures in water.

Nanosheets of an Organic Molecular Assembly from Aqueous Medium Exhibit High Solid-State Emission and Anisotropic Charge-Carrier Mobility

A π-conjugated amphiphilic diketopyrrolopyrrole (PDPP-Amphi) forms crystalline 2D supramolecular nanosheets in water when compared to that from methyl cyclohexane. These nanosheets exhibit high fluorescence quantum yield in the solid-state with anisotropic charge-carrier mobility of 0.33 cm² V^-1 s^-1 .

Carbohydrate-based amphiphilic nano delivery systems for cancer therapy

Nanoparticles (NPs) are novel drug delivery systems that have been attracting more and more attention in recent years, and have been used for the treatment of cancer, infection, inflammation and other diseases. Among the numerous classes of materials employed for constructing NPs, organic polymers are outstanding due to the flexibility of design and synthesis and the ease of modification and functionalization. In particular, NP based amphiphilic polymers make a great contribution to the delivery of poorly-water soluble drugs. For example, natural, biocompatible and biodegradable products like polysaccharides are widely used as building blocks for the preparation of such drug delivery vehicles. This review will detail carbohydrate based amphiphilic polymeric systems for cancer therapy. Specifically, it focuses on the nature of the polymer employed for the preparation of targeted nanocarriers, the synthetic methods, as well as strategies for the application and evaluation of biological activity. Applications of the amphiphilic polymer systems include drug delivery, gene delivery, photosensitizer delivery, diagnostic imaging and specific ligand-assisted cellular uptake. As a result, a thorough understanding of the relationship between chemical structure and biological properties facilitate the optimal design and rational clinical application of the resulting carbohydrate based nano delivery systems for cancer therapy.

Smart Organic Two-Dimensional Materials Based on a Rational Combination of Non-covalent Interactions

Rational design of organic 2D (O2D) materials has made some progress, but it is still in its infancy. A class of self-assembling small molecules is presented that form nano/microscale supramolecular 2D materials in aqueous media. A judicial combination of four different intermolecular interactions forms the basis for the robust formation of these ultrathin assemblies. These assemblies can be programmed to disassemble in response to a specific protein and release its non-covalently bound guest molecules.

Disk-like micelles with cylindrical pores from amphiphilic polypeptide block copolymers

An unprecedented 2-dimensional disk-like micelle with cylindrical pores was achieved by self-assembly of amphiphilic block copolypeptides PEG-b-PBLG with an α-helical conformation of PBLG blocks.

Small molecule based N-phenyl carbazole substituted diketopyrrolopyrroles as donors for solution-processed bulk heterojunction organic solar cells

We report two acetylene-bridged small molecules DPP5 and DPP6 with low HOMO–LUMO gaps as donors along with PC₇₁BM as an acceptor for the fabrication of solution-processed bulk heterojunction solar cells.

Controlled self-assembly of a pyrene-based bolaamphiphile by acetate ions: from nanodisks to nanofibers by fluorescence enhancement

In this paper, a pyrene moiety is incorporated into a bolaamphiphile to form a novel molecule denoted PRB. Above the critical micelle concentration, PRB forms nanodisks in the aqueous solution. The addition of acetate ions induces a morphological change in self-assembled aggregates, which convert into nanofibers with a diameter of several nanometers. More interestingly, along with the morphological change, the fluorescence of the assemblies was enhanced concomitantly, which can be attributed to the binding effect of acetate ions on pyridinium head groups of PRB.

Controlled self-assembly of helical nano-ribbons formed by achiral amphiphiles

Helical nano-ribbons with a large aspect ratio were obtained through the self-assembly of an achiral amphiphile. The symmetry breaking is attributed to the orderly but twisted stacking of terpyridine groups. In addition, the morphology of the assemblies can be tuned by the coordination between terpyridine and Zn(2+) ion.

Two-dimensional soft nanomaterials: a fascinating world of materials

The discovery of graphene has triggered great interest in two-dimensional (2D) nanomaterials for scientists in chemistry, physics, materials science, and related areas. In the family of newly developed 2D nanostructured materials, 2D soft nanomaterials, including graphene, Bx Cy Nz nanosheets, 2D polymers, covalent organic frameworks (COFs), and 2D supramolecular organic nanostructures, possess great advantages in light-weight, structural control and flexibility, diversity of fabrication approaches, and so on. These merits offer 2D soft nanomaterials a wide range of potential applications, such as in optoelectronics, membranes, energy storage and conversion, catalysis, sensing, biotechnology, etc. This review article provides an overview of the development of 2D soft nanomaterials, with special highlights on the basic concepts, molecular design principles, and primary synthesis approaches in the context.

Bolaamphiphiles: a pharmaceutical review

The field of drug discovery is ever growing and excipients play a major role in it. A novel class of amphiphiles has been discussed in the review. The review focuses on natural as well as synthetic bolaamphiphiles, their chemical structures and importantly, their ability to self assemble rendering them of great use to pharmaceutical industry. Recent reports on their ability to be used in fabrication of suitable nanosized carriers for drug as well as genes to target site, has been discussed substantially to understand the potential of bolaamphiphiles in field of 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.

Asymmetric and symmetric bolaform supra-amphiphiles: formation of imine bond influenced by aggregation

A series of bolaform supra-amphilphiles with different symmetries were fabricated through dynamic benzoic imine bond formation. The pH dependence of imine formations of these supra-amphiphiles were characterazied. We found that the extent of the imine formation of these supra-amphiphies were different. The supra-amphiphiles with a poorer symmetry always exhibited a lower imine formation at a given pH. Therefore, the varied extent of imine bond formation indicate the different aggregations of these supra-amphilphiles, which are controlled by the molecular symmetry of the supra-amphiphiles.

Syntheses, Structures, Characterisation, and Spectroscopic Properties of CuI and AgI Complexes with Extended C–H···π and π···π Interactions

Based on the ligands N,N′-bis(pyridin-2-ylmethylene)benzene-1,4-diamine (pmb) and N,N′-bis(pyridin-2-ylmethylene)biphenyl-4,4′-diamine (pmbb), the three compounds [Cu2(pmb) (PPh3)2(Cl)2] (1), [Cu2(pmbb)(CH3CN)2(PPh3)2](BF4)2·2DMF (2), and [Ag2(pmbb)(PPh3)2] (ClO4)2 (3) have been synthesised and characterised. Structural analysis reveals that all of these complexes contain 1D supramolecular arrays, with different variations in π-stacking patterns and intermolecular C–H···π interactions. Crystal structures of 1 and 2 contain 1D tape-like arrays formed by C–H···π and π···π interactions, and an ordered-layer-lattice of DMF and BF4– in 2 is located between the one-dimensional array. For 3, π-stacking interactions lead to the construction of 1D supramolecular arrays and a 2D network. The results indicate that C–H···π and π···π interactions play an important role in the construction of the supramolecular structure. In addition, the absorption peaks of complexes 1 and 3 in the solid state at room temperature show intraligand charge transfer and metal-to-ligand charge transfer absorptions. The optical and fluorescent properties of 2 were also studied in acetonitrile solution at room temperature.

Controlling the self-assembly of cationic bolaamphiphiles: hydrotropic counteranions determine aggregated structures

The size and substitution pattern of hydrotropic counteranions determine the aggregated structures of cationic bolaamphiphiles.

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.

Polyprodrug amphiphiles: hierarchical assemblies for shape-regulated cellular internalization, trafficking, and drug delivery

Solution self-assembly of block copolymers (BCPs) typically generates spheres, rods, and vesicles. The reproducible bottom-up fabrication of stable planar nanostructures remains elusive due to their tendency to bend into closed bilayers. This morphological vacancy renders the study of shape effects on BCP nanocarrier-cell interactions incomplete. Furthermore, the fabrication of single BCP assemblies with built-in drug delivery functions and geometry-optimized performance remains a major challenge. We demonstrate that PEG-b-PCPTM polyprodrug amphiphiles, where PEG is poly(ethylene glycol) and PCPTM is polymerized block of reduction-cleavable camptothecin (CPT) prodrug monomer, with >50 wt % CPT loading content can self-assemble into four types of uniform nanostructures including spheres, large compound vesicles, smooth disks, and unprecedented staggered lamellae with spiked periphery. Staggered lamellae outperform the other three nanostructure types, exhibiting extended blood circulation duration, the fastest cellular uptake, and unique internalization pathways. We also explore shape-modulated CPT release kinetics, nanostructure degradation, and in vitro cytotoxicities. The controlled hierarchical organization of polyprodrug amphiphiles and shape-tunable biological performance opens up new horizons for exploring next-generation BCP-based drug delivery systems with improved efficacy.

A novel diblock copolymer with a supramolecular polymer block and a traditional polymer block: preparation, controllable self-assembly in water, and application in controlled release

A novel diblock copolymer with a hydrophobic supramolecular polymer block and a hydrophilic traditional polymer block has been prepared. Control over the chain length ratio of the two blocks is obtained by simply changing the concentration proportion of the monomer of the supramolecular polymer block to the traditional polymer block in solution. When the chain length ratio of the two blocks is changed, the formation of various self-assembly morphologies is achieved.

Growth mechanisms of 2D organic assemblies generated from dialkylated melaminium derivatives: the length difference of the two alkyl chains that matters

This research is aimed to understand the growth mechanisms for self-assembly of dialkylated melamine derivatives. The dialkylated melamine derivatives with different alkyl chains (Mela-m-n) are able to self-assemble with hydrochloric acid in dichloromethane to form 2D organic assemblies, exhibiting similar lamellar structures as Mela-n·HCl with identical alkyl chains. The most interesting finding is that the growth mechanism of Mela-n·HCl with identical alkyl chains is revealed to be layer growth, while Mela-m-n·HCl with asymmetric alkyl chains adopts a spiral growth mechanism. The asymmetric alkyl chains in Mela-m-n may lead to the formation of dislocation, which is responsible for the spiral growth mechanism.

Bolaform surfactants with polyoxometalate head groups and their assembly into ultra-small monolayer membrane vesicles

Surfactants are indispensable in established technologies as detergents or emulsification agents, and also in recent studies for controlling the growth of nanoparticles or for creating nanocarriers. Although the properties of conventional, organic surfactants are thoroughly explored, strong interest persists in surfactants that possess unique features inaccessible for ordinary systems. Here we present dipolar, bolaform surfactants with a head group comprising of 11 tungsten atoms. These novel compounds are characterized by an exceptionally low critical self-organization concentration, which leads to monolayer vesicles with a diameter of only 15 nm, that is, substantially smaller than for any other system. The membrane of the vesicles is impermeable for water-soluble and oil-soluble guests. Control over release kinetics, which can be followed via the quantitative fluorescence quenching of confined fluorophores, is gained by means of pH adjustments.