Supramolecular Polypseudorotaxane Research Articles

Rare silver bromide clustered supramolecular polypseudorotaxane: Preparation and its application in photocatalytic degradation of organic compounds

Rare silver bromide clustered supramolecular polypseudorotaxane: Preparation and its application in photocatalytic degradation of organic compounds

α-Cyclodextrin-Based Polypseudorotaxane Hydrogels.

Supramolecular hydrogels that are based on inclusion complexes between α-cyclodextrin and (co)polymers have gained significant attention over the last decade. They are formed via dynamic noncovalent bonds, such as host–guest interactions and hydrogen bonds, between various building blocks. In contrast to typical chemical crosslinking (covalent linkages), supramolecular crosslinking is a type of physical interaction that is characterized by great flexibility and it can be used with ease to create a variety of “smart” hydrogels. Supramolecular hydrogels based on the self-assembly of polypseudorotaxanes formed by a polymer chain “guest” and α-cyclodextrin “host” are promising materials for a wide range of applications. α-cyclodextrin-based polypseudorotaxane hydrogels are an attractive platform for engineering novel functional materials due to their excellent biocompatibility, thixotropic nature, and reversible and stimuli-responsiveness properties. The aim of this review is to provide an overview of the current progress in the chemistry and methods of designing and creating α-cyclodextrin-based supramolecular polypseudorotaxane hydrogels. In the described systems, the guests are (co)polymer chains with various architectures or polymeric nanoparticles. The potential applications of such supramolecular hydrogels are also described.

Cucurbit[8]uril-Mediated Polypseudorotaxane for Enhanced Lanthanide Luminescence Behavior in Water.

A novel supramolecular polypseudorotaxane was successfully constructed with pseudo[3]rotaxanes between pyridine-2,6-dicarboxylic acid imidazolium (G1) and cucurbit[8]uril (CB[8]) and the subsequent coordination with lanthanide ions. Significantly, compared with the pyridine-2,6-dicarboxylic acid imidazolium complex G1@Tb3+, CB[8]-mediated polypseudorotaxane CB[8]@G12@Tb3+ not only displayed enhanced lanthanide luminescence behavior with a 29.1-fold time enhancement (from 45.76 μs to 1.33 ms) of the excited-state lifetime (τ) and a 8.7-fold increase (from 0.89% to 7.81%) in the quantum yield (Φ) but also exhibited a specific fluorescence response to antibiotics in an aqueous solution and a solid film.

Construction of anion‐responsive crosslinked polypseudorotaxane based on molecular recognition of pillar[5]arene

ABSTRACTA pillar[5]arene pendant polymer (Poly‐P[5]A) is synthesized via ROMP using Grubb's first‐generation catalyst. GPC analysis of the polymer suggested ~30 pendant pillar[5]arene units in the polymer. Supramolecular polypseudorotaxane assembly is constructed by intermolecularly crosslinking pendant pillar[5]arene units using a bispyridinium guest via host–guest complexation. Formation of the polypseudorotaxane assembly is characterized by 1D/2D NMR techniques and DLS analysis. Moreover, anion‐responsiveness of the polypseudorotaxane assembly is demonstrated by 1H NMR spectroscopic analysis using chloride anion as external stimulus. Scanning electron microscopic analysis of the poly‐P[5]A showed breath‐figure assembly and upon crosslinking with G.2PF6 the polymer self‐assemble to give a supramolecular polymer network. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1508–1515

Mobility of Water and Polymer Species and Rheological Properties of Supramolecular Polypseudorotaxane Gels Suitable for Bone Regeneration.

The aim of this work was to prepare polypseudorotaxane-based supramolecular gels combining αCD with two temperature-responsive copolymers of different architecture (i.e., linear poloxamer P and X-shaped poloxamine T), at the lowest concentration as possible to form syringeable depots, and to shed light on the self-diffusion and spatial closeness of all components (including water) which in turn may determine the cooperative self-assembly phenomena and the performance of the gels at the macroscopic level. The exchange rate between bound water and bulk water was measured with a novel NMR experiment Water Diffusion Exchange-Diffusion Optimized Spectroscopy (WDE-DOSY). Polypseudorotaxane formation caused opposite effects on the mobility of αCD species (decreased) and internal water (increased) but did not affect PPO-water interaction. Consequently, designed ternary P/T/αCD supramolecular gels exhibited in situ gelling at body temperature could host large amounts of PLA/PLGA microspheres and behaved as porous 3D-scaffolds for mesenchymal stem cells (MSCs) supporting their osteogenic differentiation. Interestingly, the gels withstood freeze-drying and reconstitution with minor changes in inner structure and rheological properties. The gathered information may help to understand better the supramolecular gels and provide tools for the rational design of syringeable bone scaffolds that can simultaneously accommodate cells and drug microcarriers for efficient tissue regeneration.

Supramolecular polypseudorotaxane gels for controlled delivery of rAAV vectors in human mesenchymal stem cells for regenerative medicine

The aim of this work was to investigate, for the first time, the possibility of using supramolecular polypseudorotaxane gels as scaffolds that can durably deliver rAAV vectors for applications in cartilage regeneration. Dispersions of Pluronic® F68 (PF68) or Tetronic® 908 (T908) containing either hyaluronic acid (HA) or chondroitin sulfate (CS) were prepared in PBS. Then, alpha-cyclodextrin (αCD) was added to some dispersions to form polypseudorotaxane gels. Polysaccharides and αCD reinforced the viscoelasticity of the gels, which could withstand autoclaving without changes. In vitro release of rAAV vectors and subsequent transduction of human mesenchymal stem cells (hMSCs) by rAAV vectors from the release medium and from gels in direct contact with the cells were investigated. Compared with free vectors, the gels provided higher levels of transgene expression. CS (or HA)/PF68/αCD gels rapidly released rAAV vectors while CS (or HA)/T908/αCD gels provided sustained release probably due to different interactions with the viral vectors. Incorporation of αCD into CS (or HA)/PF68 gels resulted on higher rAAV concentrations and sustained levels of transgene expression over time. HA increased the bioactivity and cytocompatibility of the gels, especially those based on T908. Overall, combining rAAV gene transfer with polypseudorotaxane gels may provide new, promising tools for human tissue engineering and regenerative medicine strategies.

Two novel cation-induced supramolecular polymers with 2-3D polymeric cuprous thiocyanate frameworks: Synthesis, characterization and photocatalytic activities for the degradation of organic dye contaminants

In order to systematically explore the photocatalytic activity of the inorganic–organic supramolecular polymers induced by 1,1′-(1,n-alkylidene)bis[4-methylpyridinium] (n=1–2) cations, two novel cation-induced compounds, {(bmpm) [Cu2(SCN)4]}n (bmpm=1,1′-methylenebis[4-methylpyridinium] (1) and {(bmpe) [Cu2(SCN)4]}n (bmpe=1,1′-(1,2-ethanediyl)bis[4-methylpyridinium] (2) were obtained and characterized by X-ray crystallography. Compound 1 has a 3D framework with the cations trapped within host network cavities. Compound 2 possesses an infinite 2D supramolecular polypseudorotaxane structure linked by bridging thiocyanate groups. The third-order NLO, optical band gaps and photocatalytic activities of 1 and 2 were also evaluated. Remarkably, both 1 and 2 exhibited good photocatalytic abilities.

Dendrimer-like supramolecular nanovalves based on polypseudorotaxane and mesoporous silica-coated magnetic graphene oxide: a potential pH-sensitive anticancer drug carrier

In the present research, two types of drug carriers based on mesoporous silica-coated magnetic graphene oxide, Fe3O4@GO@mSiO2, were synthesised and the pH-responsive behaviour for doxorubicin release was investigated. One type of the carrier was dendrimer-like multi ethylene amine grafted on Fe3O4@GO@mSiO2 and the other was dendrimer-like supramolecular polypseudorotaxane. Herein, α-cyclodextrin was used in the structure of supramolecular nanoparticles as a gatekeeper to inhibit the drug from escaping at neutral pH (the pH of healthy tissue). The drug release profile showed that the supramolecular nanocarrier was more sensitive to the pH changes. The content of drug release was about 100% at pH 5.5 (endosomal pH) during 48 h; but it was zero at pH 7.4. Also, the dendrimer structure facilitated the triggered release of doxorubicin.

Chitosan based supramolecular polypseudorotaxane as a pH-responsive polymer and their hybridization with mesoporous silica-coated magnetic graphene oxide for triggered anticancer drug delivery

Chitosan based polyseudorotaxane was designed as a pH-responsive supramolecular polymeric shell around the mesoporous silica-coated magnetic graphene oxide (Fe3O4@GO@mSiO2). It was used for doxorubicin delivery at cancerous tissue in a controlled manner. The core-shell nanocarrier was formed due to electrostatic interaction between chitosan and carboxylated surface of Fe3O4@GO@mSiO2. The maximum release occurred at pH 5.5 (pH of endosomes) because the shell collapsed at this pH. The drug nanocarrier has potential application in tumor therapy due to good pH-sensitive behavior, improved solubility and high colloidal stability in biological media.

Fluorescent supramolecular polypseudorotaxane architectures with Ru(II)/tri(bipyridine) centers as multifunctional DNA reagents.

A water-soluble supramolecular polypseudorotaxane was prepared via the host-guest interaction of cucurbit[8]uril and the Ru(bpy)3 complex with bis-naphthalene groups. By employing the intrinsic properties of the Ru(bpy)3 complex, the linear polypseudorotaxane can induce DNA condensation, be used as an inhibitor for DNA cleavage enzymes, and trace the translocation of DNA into 293T cells efficiently.

Pillar[5]arene-based supramolecular polypseudorotaxane polymer networks constructed by orthogonal self-assembly

A novel pillar[5]arene-based supramolecular polypseudorotaxane network constructed by orthogonal self-assembly has been successfully fabricated. The obtained supramolecular polypseudorotaxane polymer was formed by a combination of two different non-covalent interactions, quadruple hydrogen bonding and pillararene-based host–guest interactions. Furthermore, a translucent film could be generated from the combination of this supramolecular polymer with PEG-2000 as the polymer matrix. The present study will provide a convenient and efficient way for the creation of pillararene-based advanced supramolecular materials.

Supramolecular Anchoring of DNA Polyplexes in Cyclodextrin-Based Polypseudorotaxane Hydrogels for Sustained Gene Delivery

A cyclodextrin-based supramolecular hydrogel system with supramolecularly anchored active cationic copolymer/plasmid DNA (pDNA) polyplexes was studied as a sustained gene delivery carrier. A few biodegradable triblock copolymers of methoxy-poly(ethylene glycol)-b-poly(ε-caprolactone)-b-poly[2-(dimethylamino)ethyl methacrylate] (MPEG-PCL-PDMAEMA) with well-defined cationic block lengths were prepared to condense pDNA. The MPEG-PCL-PDMAEMA copolymers exhibit good ability to condense pDNA into 275-405 nm polyplexes with hydrophilic MPEG in the outer corona. The MPEG corona imparted greater stability to the pDNA polyplexes and also served as an anchoring segment when the pDNA polyplexes were encapsulated in α-CD-based supramolecular polypseudorotaxane hydrogels. More interestingly, the resultant hydrogels were able to sustain release of pDNA up to 6 days. The pDNA was released in the form of polyplex nanoparticles as it was bound electrostatically to the cationic segment of the MPEG-PCL-PDMAEMA copolymers. The bioactivity of the released pDNA polyplexes at various durations was further investigated. Protein expression level of pDNA polyplexes released over the durations was comparable to that of freshly prepared PEI polyplexes. Being thixotropic and easily prepared without using organic solvent, this supramolecular in situ gelling system has immense potential as an injectable carrier for sustained gene delivery.

Role of cooperative templates in the self-assembly process of microporous structures: syntheses and characterization of 12 new silver halide/thiocyanate supramolecular polymers

12 new cation-templated complexes, {(BMPB)[AgI3]} (BMPB = 1, 4-bis (methylpyridinium) benzene) (1), {(BPE)2[Ag2I6]} (BPE = 1, 2-bis (pyridinium) ethane) (2), {(BPB)[Ag2I4]} (BPB = 1, 4-bis (pyridinium) butane) (3), {(BPH)[Ag2I4]} (BPH = 1, 7-bis (pyridinium) heptane) (4), {(DIBP)[Ag2I4]} (DIBP = 1, 1′-diisopropyl-4, 4′-bipyridinium) (5), {(BPB)[Ag2Br4]} (6), {(BPP)[Ag2Br4]} (=1, 5-bis (pyridinium) pentane) (7), {(DEBP)[Ag2Br4]} (DEBP = 1, 1′-diethyl-4, 4′-bipyridinium) (8), {(BDMLB)[Ag2Br4]} (BDMLB = 1, 4-bis (dimethylimidazolium) butane) (9), {(BPIB·Br)[Ag(NCS)2]} (BPIB·Br = butane phenanthroline bromide) (10), {(DABP)[Ag4I6]} (DABP = 1, 1′-diamyl-4, 4′-bipyridinium) (11), {(BMLB)[Ag2Br2(NCS)2]} (BMLB = 1, 4-bis (methylimidazolium) butane) (12), have been synthesized via the self-assembly reaction in solution. Owing to the cooperative template effects from organic cations and halide/thiocyanate anion compounds 1–11 contain a mononuclear anion structure [AgI3]2− (1), a dimeric anion [Ag2I6]4− (2), linear chain [Ag2X4]2− (3–10) and a cubane-like based one-dimensional anionic chain [Ag4I6]2− (11) that are enclosed into the different cationic channels formed from the pyridinium, phenanthrolinium and imidazolium. While for 12, the compound possesses an infinite 2D supramolecular polypseudorotaxane penetrated by geminal dicationic groups.

Three novel cation-templated metal thiocyanates with 1-2D polypseudorotaxane frameworks

Three novel cation-templated complexes, {(BPE)3[Ag4Br4(SCN)6]}n (1), {(DEBP) [Cu2(SCN)4]}n (2) and {(DIBP) [Cu2(SCN)4]}n (3) [BPE = 1, 2-bis (pyridinium) ethane; DEBP = 1, 1′-diethyl-4, 4′-bipyridinium dibromide; DIBP = 1, 1′-diisopentyl-4, 4′-bipyridinium], have been synthesized viaself-assembly reaction in solution. Complex 1 possesses a one-dimensional polyrotaxane architecture with the organic cation BPE trapped in it, whereas both compounds 2 and 3 are infinite 2D supramolecular polypseudorotaxane, linked by bridging thiocyanate groups. All compounds were further characterized with IR spectra, thermal analysis, ultraviolet and fluorescence properties.

Supramolecular Polypseudorotaxane with Conjugated Polyazomethine Prepared Directly from Two Inclusion Complexes of β-Cyclodextrin with Tolidine and Phthaldehyde

The supramolecular polypseudorotaxane (3) with π-conjugated polyazomethine is directly synthesized by the polycondensation of two simple inclusion complexes of β-cyclodextrin/o-tolidine (1) and β-cyclodextrin/p-phthaldehyde (2) and is comprehensively characterized by NMR, FTIR, circular dichroism spectra, powder X-ray diffraction, thermogravimetric (TG) and differential thermal analysis (DTA), scanning electron microscopy (SEM), and scanning tunneling microscopy (STM) both in solution and in the solid state. The results obtained have revealed linear microstructure of polypseudorotaxane 3 and different photophysical behavior as compared with the π-conjugated polyazomethine backbone (4). The present investigations prove a simple method for preparing supramolecular polypseudorotaxane by different complexes, which possess the potential to serve as molecular devices/machines and optical materials.