Supramolecular self-assembly of inclusion complexes of a multiarm hyperbranched polyether with cyclodextrins

Guest-guided anchoring patterns of cyclodextrin supramolecular microcrystals on droplet surfaces

The growth of cyclodextrin inclusion complexes (ICs) on oil/water interfaces represents a beautiful example of spontaneous pattern formation in nature. How the supramolecules evolve remains a challenge because surface confinement can frustrate microcrystal growth and give rise to unusual phase transitions. Here we investigate the self-assembly of ICs on droplet surfaces using microfluidics, which allows directly visualizing packing, wetting and ordering of the microcrystals anchored on the surface. The oil guests of distinct molecular structures can direct the assembly of the ICs and largely affect anchoring dynamics of the ICs microcrystals, leading to a range of behaviors including orientating, slipping, buckling, jamming, or merging. We discuss the behaviors observed in terms of the flexibility of the building blocks, which offers a new degree of freedom through which to tailor their properties and gives rise to a striking feature of anchoring patterns that have no counterpart in normal colloidal crystals.

A Bioresponsive Diselenide-functionalized Hydrogel with Cascade Catalytic Activities for Enhanced Local Starvation- and Hypoxia-Activated Melanoma Therapy

Glutathione (GSH) consumption-enhanced cancer therapies represent important potential cancer treatment strategies. Herein, we developed a new multifunctional diselenide-crosslinked hydrogel with glutathione peroxidase (GPx)-like catalytic activity for GSH depletion-enhanced glucose oxidase (GOx)-mediated tumor starvation and hypoxia-activated chemotherapy. By increasing acid and H₂O₂ during GOx-induced tumor starvation, the degradation of the multiresponsive scaffold could be promoted, which led to accelerated release of the loaded drugs. Meanwhile, the overproduced H₂O₂ led to accelerated intracellular GSH consumption under the cascade catalysis of small molecular selenides released from the degraded hydrogel, further enhancing the curative effect of in situ H₂O₂ and subsequent multimodal cancer treatment. Following the GOx-induced amplification of hypoxia, tirapazamine (TPZ) was transformed into the highly toxic benzotriazinyl radical (BTZ·), exhibiting enhanced antitumor activity. This GSH depletion-augmented cancer treatment strategy effectively boosted GOx-mediated tumor starvation and activated the hypoxia drug, leading to significantly enhanced local anticancer efficacy. STATEMENT OF SIGNIFICANCE: There has been a growing interest in depleting intracellular GSH as a potential strategy for improving ROS-based cancer therapy. Herein, a bioresponsive diselenide-functionalized dextran-based hydrogel with GPx-like catalytic activity was developed for GSH consumption-enhanced local starvation- and hypoxia-activated melanoma therapy. Results showed that the overproduced H₂O₂ led to accelerated intracellular GSH consumption under the cascade catalysis of small molecular selenides released from the degraded hydrogel, further enhancing the curative effect of in situ H₂O₂ and subsequent multimodal cancer treatment.

Novel self-assembled nanogels of PEG-grafted poly HPMA with bis(α-cyclodextrin) containing disulfide linkage: synthesis, bio-disintegration, and in vivo biocompatibility

Synthesis of self-assembled nanogels of PEG-grafted poly HPMA with bis(α-cyclodextrin) containing disulfide linkage.

Supramolecular hyperbranched polymers

This feature article presents a systematic summary of the synthesis strategies including direct and indirect approaches for obtaining supramolecular hyperbranched polymers (SHPs).

Towards Cyclodextrin-Based Supramolecular Materials

Inclusion complexation between cyclodextrins (CDs) and various guests has been extensively investigated in supramolecular chemistry. Besides CDs, there are several important macrocyclic host families, such as crown ethers and cucurbiturils. Until now, the contribution of these other families to macromolecular self-assembly has been small compared to CDs. This chapter will focus on CDs as hosts for interaction with guest monomers to form hydrogels. CD interactions with other monomers were made possible depending on proper molecular recognition. Macroscopic molecular recognition can be categorized by three types of interactions: main chain (polyrotaxane), side chain, and sequential complexes. Utilizing CD as host molecule, polymers such as polyethers, cationic polymers, polyamines, polyesters, π-conjugated polymers, polyolefins, polyamides, polyurethanes, and inorganic polymers could interact to form inclusion complexes. This chapter will attempt to discuss these studies. Depending on the functional groups attached to the polymeric component, supramolecular formation can be altered based on the stimuli response. Introducing polymer side chains or groups that respond selectively towards external stimuli could affect the hydrogel formation. This chapter also discusses the stimuli response of such systems.

Electrochemical redox responsive polymeric micelles formed from amphiphilic supramolecular brushes

The end-decorated homopolymer poly(ε-caprolactone)-ferrocene threaded onto a β-cyclodextrin-functionalized main-chain polymer can form a class of amphiphilic noncovalent graft copolymers based on the host-guest interactions of the terminal groups on the side chains. These new supramolecular polymer brushes can further self-assemble into micellar aggregates that exhibit reversible assembly and disassembly behavior under an electrochemical redox trigger, which opens up a new route to building dynamic block copolymer topologies.

Recent developments and applications of bioinspired dendritic polymers

This review highlights the bioinspired applications of dendritic polymers, focusing on their structure–function relationship to natural biomolecules such as proteins.

Hyperbranched polymers: advances from synthesis to applications

This review summarizes the advances in hyperbranched polymers from the viewpoint of structure, click synthesis and functionalization towards their applications in the last decade.

Preparation of water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups and their micelles behavior, anticoagulant effect and cytotoxicity

Biocompatibility of nanoparticles has been attracting great interest in the development of nanoscience and nanotechnology. Herein, the aliphatic water-soluble hyperbranched polyester nanoparticles with sulfonic acid functional groups (HBPE-SO3 NPs) were synthesized and characterized. They are amphiphilic polymeric nanoparticles with hydrophobic hyperbranched polyester (HBPE) core and hydrophilic sulfonic acid terminal groups. Based on our observations, we believe there are two forms of HBPE-SO3 NPs in water under different conditions: unimolecular micelles and large multimolecular micelles. The biocompatibility and anticoagulant effect of the HBPE-SO3 NPs were investigated using coagulation tests, hemolysis assay, morphological changes of red blood cells (RBCs), complement and platelet activation detection, and cytotoxicity (MTT). The results confirmed that the sulfonic acid terminal groups can substantially enhance the anticoagulant property of HBPE, and the HBPE-SO3 NPs have the potential to be used in nanomedicine due to their good bioproperties.

Surface hybrid self-assembly, mechanism, and crystalline behavior of a carboxyl-ended hyperbranched polyester/platinum complex

The self-assembly of hyperbranched polymers has attracted much attention because of their wide application. In this article, we report a new facile surface self-assembly method for a carboxyl-ended hyperbranched polyester/platinum complex (HTD-3-Pt) and obtain ordered structural microrods with a length of 10-20 μm and a width of 1 μm. The length and diameter of the self-assembled microrods could be increased to 300-600 μm and 4-5 μm, respectively, by hierarchical self-assembly. The main factors affecting the morphology of the self-assemblies, including temperature, time, solvent and solubility parameter, and relative humidity were discussed by transmission/reflection polarizing optical microscopy (TRPOM), SEM, and HRSEM. The indications for the coordination bond (-COOPt) included the appearance of a new peak at 1606 cm(-1) and its shifting to 1634 cm(-1) in the FT-IR spectra, the disappearance of the C 1s peak at about 288.6 eV, and the increase in the O 1s electron binding energy in the XPS spectra. Furthermore, an interesting crystal property of the HTD-3-Pt self-assemblies was discovered and confirmed by XRD. The study results from the surface self-assembly mechanism suggest that the coordination induction of the platinum ion play a key role in driving microphase separation between the intermolecular chains and end groups of the HTD-3-Pt to form the microrod self-assemblies. Another interesting finding was that HTD-3-Pt showed a higher catalytic activity for hydrosilylation than did a traditional homogeneous catalyst.

Photoluminescent hyperbranched poly(amido amine) containing β-cyclodextrin as a nonviral gene delivery vector

Hyperbranched poly(amido amine)s (HPAAs) containing different amounts of β-cyclodextrin (β-CD) (HPAA-CDs) were synthesized in one-pot by Michael addition copolymerization of N,N'-methylene bisacrylamide, 1-(2-aminoethyl)piperazine, and mono-6-deoxy-6-ethylenediamino-β-CD. In comparison to pure HPAA, the fluorescence intensity of HPAA-CDs was enhanced significantly while the cytotoxicity became lower. Ascribed to plenty of amino groups and strong photoluminescence, HPAA-CDs could be used as nonviral gene delivery vectors, and the corresponding gene transfection was evaluated. The experimental results indicated that HPAA-CDs condensed the plasmid DNA very well. By utilizing the fluorescent properties of HPAA-CDs, the cellular uptake and gene transfection processes were tracked by flow cytometry and confocal laser scanning microscopy without any fluorescent labeling. The transfection efficiencies of HPAA-CDs were similar to that of pure HPAA. In addition, the inner cavities of β-CDs in HPAA-CDs could be used to encapsulate drugs through host--guest interaction. Therefore, the HPAA-CDs may have potential application in the combination of gene therapy and chemotherapy.

Self-assembly of hyperbranched polymers and its biomedical applications

Hyperbranched polymers (HBPs) are highly branched macromolecules with a three-dimensional dendritic architecture. Due to their unique topological structure and interesting physical/chemical properties, HBPs have attracted wide attention from both academia and industry. In this paper, the recent developments in HBP self-assembly and their biomedical applications have been comprehensively reviewed. Many delicate supramolecular structures from zero-dimension (0D) to three-dimension (3D), such as micelles, fibers, tubes, vesicles, membranes, large compound vesicles and physical gels, have been prepared through the solution or interfacial self-assembly of amphiphilic HBPs. In addition, these supramolecular structures have shown promising applications in the biomedical areas including drug delivery, protein purification/detection/delivery, gene transfection, antibacterial/antifouling materials and cytomimetic chemistry. Such developments promote the interdiscipline researches among surpramolecular chemistry, biomedical chemistry, nano-technology and functional materials.

Construction and application of a pH-sensitive nanoreactor via a double-hydrophilic multiarm hyperbranched polymer

A double-hydrophilic multiarm hyperbranched polymer with a hyperbranched poly(amidoamine) (HPAMAM) core and many poly(ethylene glycol) monomethyl ether (MPEG) arms connected by pH-sensitive acylhydrazone bonds (HPAMAM-g-MPEG) was successfully prepared. Benefiting from the cationic dendritic core and PEGylation shell, the double-hydrophilic multiarm hyperbranched polymer was used as a nanoreactor for CdS quantum dots (CdS QDs) synthesis in aqueous solution. The obtained HPAMAM-g-MPEG and CdS/HPAMAM-g-MPEG nanocomposites were carefully characterized by (1)H NMR, (13)C NMR, Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis), fluorescence spectroscopy (FL), dynamic light scattering (DLS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and electronic dispersive X-ray spectroscopy (EDS) analysis. Both (1)H NMR and fluorescence spectroscopy investigations confirmed that the acylhydrazone linkage between the dendritic core and linear arms was readily broken under acidic condition (pH <5.5). When MPEG arms departed from the HPAMAM core, the fluorescence intensity of CdS/HPAMAM-g-MPEG nanocomposites greatly increased. Such pH-responsive behavior of CdS/HPAMAM-g-MPEG nanocomposites was utilized as an exploration of a novel fluorescence probe in an acidic lysosome exemplified by COS-7 cells.

Controlling the particle size of interpolymer complexes through host-guest interaction for drug delivery

A new method to adjust the particle size of interpolymer complexes has been developed by introduction of host-guest interaction into the dilute aqueous solution of poly(acrylic acid) (PAA) and poly(ethylene glycol) (PEG). Because of the cooperative hydrogen-bonding interaction, PAA can form the interpolymer complexes with PEG. Putting beta-cyclodextrin (beta-CD) into dilute PAA/PEG aqueous solution, the competition between host-guest and hydrogen-bonding interactions happens. The beta-CD/PAA/PEG ternary systems have been well characterized by ultraviolet-visible absorption spectroscopy (UV-vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), diffusion NMR spectroscopy, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), and solid-state (13)C NMR spectroscopy. The results indicate that the hydrophobic cavity of beta-CD is threaded by linear polymers so that the hydrophilicity of PAA/PEG interpolymer complexes is improved greatly. Adjusting the amounts of beta-CD, the particle size of the interpolymer complexes can be readily controlled. The low cytotoxicity of various beta-CD/PAA/PEG ternary complexes has been confirmed using the MTT assay in COS-7 cell line. Doxorubicin (DOX), an anticancer drug, has been encapsulated into the beta-CD/PAA/PEG ternary complexes. The DOX-loaded beta-CD/PAA/PEG ternary complexes have been analyzed by confocal laser scanning microscopy (CLSM), flow cytometry analysis, and the MTT assay against human cervical carcinoma cell (Hela). The results indicate that beta-CD/PAA/PEG ternary complexes with controlled particle size could be used as safe and promising drug carriers.

Iron-induced cyclodextrin self-assembly into size-controllable nanospheres

Iron-induced self-assembly of beta-cyclodextrin, beta-CD, into size controllable nanospheres with a well-defined spherical morphology and a relatively narrow size distribution was formed when acetone was added to a solution of beta-CD with iron(II) acetate, Fe(OAc)(2), in DMF. Thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy, and high resolution transmission electron microscopy showed that the irons were present as a well-dispersed state in the beta-CD nanospheres. In the (1)H NMR spectrum of the beta-CD/Fe(OAc)(2), beta/Fe, solution before adding acetone, the peaks corresponding to beta-CD were broadened and their spin-spin splitting had disappeared. In particular, the beta/Fe solutions were found to remain in a clean solution state at 1 week after solution preparation. These findings indicate the isolation of individual iron ions caused by the surrounding of each ion with the beta-CD molecules in the solution before the addition of acetone. X-ray crystal structure analysis, morphological observations, and N(2) adsorption and desorption experiments showed that the beta-CD nanospheres were generated by the formation of iron-embedded beta-CD primary particles with disordered cage type structure and simultaneous spherical assembly of the primary particles during the addition of acetone to the beta/Fe solution with appropriate mole ratio between beta-CD and Fe(OAc)(2). Interestingly, the size of the beta-CD nanospheres could be simply controlled by changing the speed at which acetone was added to the solution, with higher acetone addition speeds yielding smaller particles.