A hyaluronidase/temperature dual-responsive supramolecular assembly based on the anionic recognition of calixpyridinium

pH-Triggered Transition from Micellar Aggregation to a Host-Guest Complex Accompanied by a Color Change

A pH-triggered transition from micellar aggregation to a host-guest complex was achieved based on the supramolecular interactions between calixpyridinium and pyrroloquinoline quinone disodium salt (PQQ-2Na) accompanied by a color change. Our design has the following three advantages: (1) a regular spherical micellar assembly is fabricated by the supramolecular interactions between calixpyridinium and PQQ-2Na at pH 6 in an aqueous solution, (2) increasing the pH can lead to a transition from micellar aggregation to a host-guest complex due to the deprotonation of calixpyridinium, and at the same time (3) increasing the pH can lead to a color change owing to the deprotonation of calixpyridinium and the complexation of deprotonated calixpyridinium with PQQ-2Na. Benefitting from the low toxicity of calixpyridinium and PQQ-2Na, this pH-induced transition from micellar aggregation to a host-guest complex was further studied as a controllable-release model.

(Macro)molecular self-assembly for hydrogel drug delivery

Hydrogels prepared via self-assembly offer scalable and tunable platforms for drug delivery applications. Molecular-scale self-assembly leverages an interplay of attractive and repulsive forces; drugs and other active molecules can be incorporated into such materials by partitioning in hydrophobic domains, affinity-mediated binding, or covalent integration. Peptides have been widely used as building blocks for self-assembly due to facile synthesis, ease of modification with bioactive molecules, and precise molecular-scale control over material properties through tunable interactions. Additional opportunities are manifest in stimuli-responsive self-assembly for more precise drug action. Hydrogels can likewise be fabricated from macromolecular self-assembly, with both synthetic polymers and biopolymers used to prepare materials with controlled mechanical properties and tunable drug release. These include clinical approaches for solubilization and delivery of hydrophobic drugs. To further enhance mechanical properties of hydrogels prepared through self-assembly, recent work has integrated self-assembly motifs with polymeric networks. For example, double-network hydrogels capture the beneficial properties of both self-assembled and covalent networks. The expanding ability to fabricate complex and precise materials, coupled with an improved understanding of biology, will lead to new classes of hydrogels specifically tailored for drug delivery applications.

UV Accelerated Assemblies Constructed Using Calixpyridinium in Aqueous Solution

In this work, an irregular calixpyridinium-suramin sodium supramolecular assembly was constructed by the strong host-guest electrostatic interactions. More interestingly, a novel regular spherical supramolecular assembly was also fabricated by the hydrogen bonding interactions between suramin sodium and the UV accelerated addition product of deprotonated calixpyridinium in water. The same principle was also applied to construct a UV accelerated regular spherical self-assembly by the addition product of deprotonated calixpyridinium in water. Compared with the complicated and irreversible covalent connection of the light-responsive groups to the building block, which is one of the common means of obtaining light-responsive supramolecular systems, this finding not only provides a smart, facile, and universally applicable method to construct deprotonated calixpyridinium-based light-responsive host-guest systems but also provides a new idea for the development of other novel light-responsive building blocks.

Photolysis of a calixpyridinium-based supramolecular amphiphilic assembly and its selective turn-on fluorescence recognition of lysine in water

A new calixpyridinium-based light-responsive host-guest recognition motif was found in this work. This host-guest recognition motif was further discovered to be applied as a selective turn-on fluorescent sensor for lysine over other natural amino acids.

DNase I-Responsive Calixpyridinium-Mediated DNA Aggregation

In this work, cationic macrocyclic calixpyridinium was employed as a new strategy to condense DNA. Moreover, the degradation of DNA by DNase I could lead to the calixpyridinium-DNA supramolecular aggregates being dissipated. Therefore, the present system is potentially applicable as the targeted drug delivery model at DNase I-overexpressed sites.

Supramolecular Amphiphilic Assembly Formed by the Complexation of Calixpyridinium with Alimta

In this work, the host-guest interaction between calixpyridinium and anionic anticancer drug Alimta was studied in aqueous media. Spherical supramolecular amphiphilic assembly rather than simple complex was accidentally fabricated by the complexation of calixpyridinium with Alimta. It is the third kind of anionic guest to be discovered to form the higher-order assembly by the complexation of calixpyridinium besides polyanionic guest and anionic gemini surfactant guest. The finding of this assembly approach supplies a new idea to construct various self-assembly architectures in water via the complexation of calixpyridinium with anionic drugs. The resulting calixpyridinium-drug assemblies may also have the potential to adjust the effects of drugs.

Comparative Study on the Supramolecular Assemblies Formed by Calixpyridinium and Two Alginates with Different Viscosities

In this work, a comparative study on the supramolecular assemblies formed by calixpyridinium and two alginates with different viscosities was performed. We found that sodium alginate (SA) with medium viscosity (SA-M) had a better capability to induce aggregation of calixpyridinium in comparison with SA with low viscosity (SA-L) because of the stronger electrostatic interactions between calixpyridinium and SA-M. Therefore, the morphology of calixpyridinium-SA-M supramolecular aggregates was a compact spherical structure, while that of calixpyridinium-SA-L supramolecular aggregates was an incompact lamellar structure. As a result, adding much more amount of 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt to calixpyridinium-SA-M solution was required to achieve the balance of the competitive binding, and in comparison with calixpyridinium-SA-L supramolecular aggregates, calixpyridinium-SA-M supramolecular aggregates were more sensitive to alkali. However, for the same reason, in comparison with calixpyridinium-SA-M supramolecular aggregates, calixpyridinium-SA-L supramolecular aggregates were much more stable in water not only at room temperature but also at a higher temperature, and even in salt solution. Therefore, in comparison with calixpyridinium-SA-L supramolecular aggregates, calixpyridinium-SA-M supramolecular aggregates exhibited a completely opposite response to acid because of the generation of salt. Because SA is an important biomaterial with excellent biocompatibility, it is anticipated that this comparative study is extremely important in constructing functional supramolecular biomaterials.

Synthesis of Two Anionic Gemini Surfactants and Their Self-Assembly Induced by the Complexation of Calixpyridinium

The information in the literature concerned with lowering the critical aggregation concentration of anionic surfactants by macrocyclic compounds is scarce. This research develops an effective route for lowering the critical aggregation concentration of anionic gemini surfactants by the complexation of calixpyridinium. Furthermore, the size of complex self-assembled nanostructures can be well controlled by the different mixing ratio of the host and the guest.

The supramolecular polymer complexes with oppositely charged calixresorcinarene: hydrophobic domain formation and synergistic binding modes

The association of branched polyethyleneimine (PEI) with a series of octacarboxy-calixresorcinarenes bearing different low-rim substituents leads to the formation of nanosized supramolecular complexes. The PEI-macrocycle complexes have fine-tunable sizes regulated by variations in the self-association capacity of the calixresorcinarenes. In the supramolecular complexes, hydrophobic fragments of the polymer and calixresorcinarenes form cooperative hydrophobic domains which provide synergistic enhancement of guest molecule binding. The formation of the supramolecular complexes was investigated by NMR FT-PGSE, NMR 2D NOESY, DLS and TEM methods. In addition, fluorimetry and UV-vis methods were used with the help of optical probes, namely water-soluble Crystal Violet and water-insoluble Orange OT. The investigation demonstrates the first example of the formation of cooperative hydrophobic domains in supramolecular polyelectrolyte-macrocycle complexes which enhance the binding of both water-soluble and water-insoluble organic compounds. The presented supramolecular systems have potential as sensory and drug delivery systems.