Supramolecular Assembly System Research Articles

Near Infrared Light Triggered Cucurbit[7]uril-Stabilized Gold Nanostars as a Supramolecular Nanoplatform for Combination Treatment of Cancer.

Developing a spatiotemporal-controlled platform with feasible synthesis and multifunctionality is highly desirable in the field of nanomedicine. Here, we present a near-infrared (NIR)-light-triggered approach to control the supramolecular assembly system for drug release and achieve synergistic chemo-photothermal therapy for cancer. A cucurbit[7]uril (CB[7]) stabilized gold nanostar (GNS) platform is designed to encapsulate the anticancer drug camptothecin (CPT) via host-guest chemistry. Importantly, CB[7] behaves not only as a surfactant to improve the stability of GNS in the aqueous solution but also as the cage for intermolecular assembly of CPT molecules. Moreover, without the competitive complexation, the drug release could be stimulated under NIR light irradiation. Synergistic treatment of cancer can be achieved by combining chemotherapy with the photothermal effect of GNS. This work develops a NIR-light-triggered cucurbituril-based drug-release approach that opens the door for remote control of drug release in the supramolecular assembly system.

ChemInform Abstract: Supramolecular Chemistry in Microflow Fields: Toward a New Material World of Precise Kinetic Control

AbstractReview: [22 refs.

Supramolecular Chemistry in Microflow Fields: Toward a New Material World of Precise Kinetic Control.

Constructing new and versatile self-assembling systems in supramolecular chemistry is much like the development of new reactions or new catalysts in synthetic organic chemistry. As one such new technology, conventional supramolecular assembly systems have been combined with microflow techniques to control intermolecular or interpolymer interactions through precise regulation of a flowing self-assembly field. The potential of the microflow system has been explored by using various simple model compounds. Uniform solvent diffusion in the microflow leads to rapid activation of molecules in a nonequilibrium state and, thereby, enhanced interactions. All of these self-assembly processes begin from a temporally activated state and proceed in a uniform chemical environment, forming a synchronized cluster and resulting in effective conversion to supramolecules, with precise tuning of molecular (or polymer) interactions. This approach allows the synthesis of a variety of discrete microstructures (e.g., fibers, sheets) and unique supramolecules (e.g., hierarchical assemblies, capped fibers, polymer networks, supramolecules with time-delayed action) that have previously been inaccessible.

Controlled Nanopores by Supramolecular Assembly of End-Functionalized Dendrimer and Homopolymer Blend.

Supramolecular assembly of end-functionalized polymers, forming block copolymer-like supramolecules based on ionic interaction, has been utilized as a simple and facile method for generating functionalized nanoporous thin film. Here, the binary blend film of aminated poly(ethylene oxide) dendrimer (APEO-G) and sulfonated polystyrene (SPS) at a stoichiometric composition after benzene/water solvent vapor annealing exhibits spherical domains in multilayers over a large area. By controlling the number of end-functional arms of dendrimer via divergent ring-opening polymerization of ethylene oxide as well as the molecular weights of SPS, the domain sizes can be controlled ranging from mainly 34 to 54 nm, even to 131 nm. Our supramolecular-assembly system provides an alternative approach to fabricating a functional nanotemplate by easily etching domains with selective solvent treatment and leaving functional groups at the pore surfaces.

Label-free fluorometric assay for acetylcholinesterase and inhibitor screening based on supramolecular assemblies

A new, easily prepared, inexpensive and facile fluorometric assay method for screening of acetylcholinesterase (AChE) and its inhibitor is successfully established with the supramolecular assemblies of myristoylcholine and heparin. Myristoylcholine, an amphiphilic compound, is chosen as the cationic surfactant as well as the substrate for AChE. The environment-dependent dye pyrene, encapsulated in hydrophobic interiors of the supramolecular assemblies, works as the fluorescent probe. This new assay method is designed to monitor the release of the encapsulated fluorescent probe from supramolecular assemblies triggered by an enzyme hydrolysis process. Such a strategy is appealing; organic synthesis was not required due to the use of the supramolecular assembly. The supramolecular assembly system allows for the sensitive assay of AChE with a limit of detection (LOD) as low as 4 mU mL−1. The results also clearly demonstrate the usefulness of this fluorometric assay method for screening inhibitors of AChE. Given its inexpensive, simple and easy operation, this method may extend to high-throughput screening of AChE inhibitors and relevant Alzheimer's disease (AD) drug discovery.

Self-regulated supramolecular assembly driven by a chemical-oscillating reaction

A novel self-regulated supramolecular assembly (SSA) system driven by a chemical-oscillating reaction is constructed based on dynamic supramolecular interactions and the rhythm of the SSA process can be controlled by temperature.

ChemInform Abstract: “Supramolecular Wrapping Chemistry” by Helix‐Forming Polysaccharides: A Powerful Strategy for Generating Diverse Polymeric Nano‐Architectures

AbstractReview: 33 refs.

‘Supramolecular wrapping chemistry’ by helix-forming polysaccharides: a powerful strategy for generating diverse polymeric nano-architectures

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3-glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry.

Supramolecular assembly system depended on guest species based on bis-naphthane modified β-cyclodextrin dimer

The supramolecular assembly system based on bis naphtahlene modified β-cyclodextrin dimer linked with ethylenediamine unit was studied. The synthesis of the titled compound (β-1) was succeeded in a 7% synthetic yield. It was observed that β-1 showed monomer emission, which was decreased concurrently with appearance of excimer emission in an addition of guest species such as 1-adamantanol or ursodeoxycholic acid. When γ-CyD was added to the system, two types of fluorescent spectra were obtained, which was depended on guest species. It was indicated that both of naphthalene units of β-1 were included in the γ-CyD cavity in the presence of 1-adamantanol in a fashion of 2:1 complex. On the other hand, an addition of ursodeoxycholic acid gave disappearance of the excimer emission as well as increase of monomer emission. In the system, each of the appended units was trapped by the each of two γ-CyDs, which is 2:2 complex formation.

Unique molecular recognition property of bis-pyrene-modified β-cyclodextrin dimer in collaboration with γ-cyclodextrin

β-Cyclodextrin (β-CyD) dimer modified with two pyrene moieties, 6-(2-pyrenebutylate-aminoethyl)pyrenebutylate-amino-6-deoxy-bis-β-CyD (β-1) has been prepared to investigate the chemo-sensing ability for organic guests and the host–guest complexation behavior in the presence of γ-CyD. This fluorescent cyclodextrin dimer showed monomer and excimer emissions; the guest-induced emissions were observed as increase or decrease depending on the guest molecules. The sensing parameters, Δ I m / I m 0 and Δ I ex / I ex 0 , were used to describe the sensing ability of β-1, where I m 0 , I m, I ex and I ex 0 were fluorescence intensities of monomer and excimer emission, respectively, in the presence and absence of the guest and Δ I m = I m − I m 0 and Δ I ex = I ex − I ex 0 . This host particulary able to distinguish between ursodeoxycholic acid and chenodeoxycholic acid, which are related as diasteromer. It is observed that supramolecular association between the β-1 and γ-CyD was formed in the presence of 1-adamantanol and bisphenol A as a guest. In this work, we succeeded to make a new type of supramolecular assembly system based on hetero association between a guest, β-1 and γ-CyD.