Supramolecular structures based on dimeric combinations of cyclodextrin and adamantane via click chemistry

Asymmetric Cyclodextrin-Dimer-Involved Nanoassemblies by Selective Host-Guest Interactions: Concentration-Dependent Morphology Evolution and Light-Regulated Biomedical Applications

Supramolecular assembly has attracted significant attention and has been applied to various applications. Herein, a β-γ-CD dimer was synthesized to complex different guest molecules, including single-strand polyethylene glycol (PEG)-modified C60 (PEG-C60), photothermal conversion reagent (IR780), and dexamethasone (Dexa), according to the complexation constant-dependent specific selectivity. Spherical or cylindrical nanoparticles, monolayer or bilayer vesicles, and bilayer fusion vesicles were discovered in succession if the concentration of PEG-C60 was varied. Moreover, if near-infrared light was employed to irradiate these nanoassemblies, the thermo-induced morphological evolution, subsequent cargo release, photothermal effect, and singlet oxygen (1O2) generation were successfully achieved. The in vitro cell experiments confirmed that these nanoparticles possessed excellent biocompatibility in a normal environment and achieved superior cytotoxicity by light regulation. Such proposed strategies for the construction of multilevel structures with different morphologies can open a new window to obtain various host-guest functional materials and achieve further use for disease treatment.

A Multiple-Stimuli-Responsive Amphiphilic Copolymer for Antifouling and Antibacterial Functionality via a “Resistance–Kill–Release” Mechanism

In recent years, polymers with stimuli-responsive properties have been increasingly reported on due to their diverse applications. However, most of the studies have only focused on the performance of polymers under specific scenarios. The laws of changes in the properties in response to various external stimuli have been less systematically and quantitatively studied. In this paper, we prepared an amphiphilic polymer (PadaMX and PAdaM3QA−X) with temperature-, pH-, ion-, and β-cyclodextrin (β-CD)-responsive properties. According to the cloud point tested by the UV-Vis method, the lower critical soluble temperature (LCST) of PAdaM3QA−10% was more sensitive to a change in pH and less sensitive to a change in ions compared with PadaM3 due to quaternized side chains with a stronger intramolecular mutual repulsion. We then fabricated the coatings with responsive properties by immobilizing the adamantyl groups on β-CD-modified surfaces. The hydrophilicity of the coatings was improved after quaternization, as proven by the water contact angle (WCA) measurement. The antifouling and antibacterial performance was further evaluated via the fluorescence intensity of bovine serum albumin (BSA) adsorbed on the surfaces and the spread plate method. A 78.4% BSA desorption rate and a 96.8% sterilization rate were achieved by the PAdaM3QA−10% coating. In summary, this work prepared a multiple-stimuli-responsive amphiphilic copolymer for antifouling and antibacterial functionality via a “resistance–kill–release” mechanism.

Cyclodextrin-adamantane conjugates, self-inclusion and aggregation versus supramolecular polymer formation

β-Cyclodextrin conjugated to adamantane forms self-inclusion complexes instead of supramolecular polymers.

Cyclodextrin-based polymeric materials: synthesis, properties, and pharmaceutical/biomedical applications

This review describes the synthesis, properties, and, in particular, biomedical and pharmaceutical applications of an upcoming class of polymeric networks and assemblies based on cyclodextrins (CDs). CDs are cyclic oligosaccharides composed of alpha-1,4-coupled d-glucose units, which contain a hydrophobic internal cavity that can act as a host for various, generally lipophilic, guest molecules. Because of this unique physicochemical property, commonly referred to as inclusion complex formation, CDs have often been used to design polymeric materials, such as hydrogels and nanoparticles. Polymeric systems based on CDs exhibit unique characteristics in terms of mechanical properties, stimuli-responsiveness, and drug release characteristics. In this contribution, first, an outline is given of covalently cross-linked polymeric networks in which CD moieties were structurally incorporated to modulate the network strength as well as the complexation and release of low molecular weight drugs. Second, physically assembled polymeric systems are discussed, of which the formation is accomplished by inclusion complexes between polymer-conjugated CDs and various guest molecule-derivatized polymers. Due to their physical nature, these polymeric systems are sensitive to external stimuli, such as temperature changes, shear forces and the presence of competing CD-binding molecules, which can be exploited to use these systems as injectable, in situ gelling devices. In recent years, many interesting CD-containing polymeric systems have been described in literature. These systems have to be optimized and extensively evaluated in preclinical studies concerning their safety and efficacy, making future clinical applications of these materials in the biomedical and pharmaceutical field feasible.