Thermoresponsive Corannulene

Polyglycerol-Based Hydrogel as Versatile Support Matrix for 3D Multicellular Tumor Spheroid Formation

Hydrogel-based artificial scaffolds are essential for advancing cell culture models from 2D to 3D, enabling a more realistic representation of physiological conditions. These hydrogels can be customized through crosslinking to mimic the extracellular matrix. While the impact of extracellular matrix scaffolds on cell behavior is widely acknowledged, mechanosensing has become a crucial factor in regulating various cellular functions. cancer cells' malignant properties depend on mechanical cues from their microenvironment, including factors like stiffness, shear stress, and pressure. Developing hydrogels capable of modulating stiffness holds great promise for better understanding cell behavior under distinct mechanical stress stimuli. In this study, we aim to 3D culture various cancer cell lines, including MCF-7, HT-29, HeLa, A549, BT-474, and SK-BR-3. We utilize a non-degradable hydrogel formed from alpha acrylate-functionalized dendritic polyglycerol (dPG) and thiol-functionalized 4-arm polyethylene glycol (PEG) via the thiol-Michael click reaction. Due to its high multivalent hydroxy groups and bioinert ether backbone, dPG polymer was an excellent alternative as a crosslinking hub and is highly compatible with living microorganisms. The rheological viscoelasticity of the hydrogels is tailored to achieve a mechanical stiffness of approximately 1 kPa, suitable for cell growth. Cancer cells are in situ encapsulated within these 3D network hydrogels and cultured with cell media. The grown tumor spheroids were characterized by fluorescence and confocal microscopies. The average grown size of all tumoroid types was ca. 150 µm after 25 days of incubation. Besides, the stability of a swollen gel remains constant after 2 months at physiological conditions, highlighting the nondegradable potential. The successful formation of multicellular tumor spheroids (MCTSs) for all cancer cell types demonstrates the versatility of our hydrogel platform in 3D cell growth.

Gels That Serve as Mucus Simulants: A Review

Mucus is a critical part of the human body's immune system that traps and carries away various particulates such as anthropogenic pollutants, pollen, viruses, etc. Various synthetic hydrogels have been developed to mimic mucus, using different polymers as their backbones. Common to these simulants is a three-dimensional gel network that is physically crosslinked and is capable of loosely entrapping water within. Two of the challenges in mimicking mucus using synthetic hydrogels include the need to mimic the rheological properties of the mucus and its ability to capture particulates (its adhesion mechanism). In this paper, we review the existing mucus simulants and discuss their rheological, adhesive, and tribological properties. We show that most, but not all, simulants indeed mimic the rheological properties of the mucus; like mucus, most hydrogel mucus simulants reviewed here demonstrated a higher storage modulus than its loss modulus, and their values are in the range of that found in mucus. However, only one mimics the adhesive properties of the mucus (which are critical for the ability of mucus to capture particulates), Polyvinyl alcohol-Borax hydrogel.

Synthesis, electronic properties, and self-assembly of an alkylated dibenzo(biscorannulene)

The synthesis and properties of a novel fully-conjugated biscorannulene derivative were reported. This biscorannulene derivative shows self-association in solution and adopts a stacked geometry in crystal.

Diazapentabenzocorannulenium: A Hydrophilic/Biophilic Cationic Buckybowl

Polycyclic aromatic molecules are promising functional materials for a wide range of applications, especially in organic electronics. However, their largely hydrophobic nature has impeded further applications. As such, imparting high solubility/hydrophilicity to polycyclic aromatic molecules leads to a breakthrough in this research field. Herein, we report the synthesis of diazapentabenzocorannulenium, a cationic nitrogen-embedded buckybowl bearing a central imidazolium core, by a bottom-up strategy from polycyclic aromatic azomethine ylide. X-ray crystallography analyses have revealed a bowl-shaped molecular structure that is capable of forming charge-segregated one-dimensional columns by bowl-in-bowl packing. In addition to its fluorescence capabilities and high dispersibility in water, the molecule was found to selectively localize in the mitochondria of various tumor cells, showing potential as viable mitochondria-selective fluorescent probes.

Polyglycerol-Based Mucus-Inspired Hydrogels

The mucus layer is a hydrogel network that covers mucosal surfaces of the human body. Mucus has important protective properties that are related to its unique rheological properties, which are based on mucins being the main glycoprotein constituents. Mucin macromolecules entangle with one another and form a physical network that is instrumental for many important defense functions. Mucus derived from various human or animal sources is poorly defined and thus not suitable for many application purposes. Herein, a synthetic route is fabricated to afford a library of compositionally defined mucus-inspired hydrogels (MIHs). MIHs are synthesized by thiol oxidation to render disulfide bonds between the crosslinker ethoxylated trimethylolpropane tri(3-mercaptopropionate) (THIOCURE ETTMP 1300) and the linear precursors, dithiolated linear polyglycerol (LPG(SH)₂ ) or polyethylene glycol (PEG(SH)₂ ) of different molecular weights. The mixing ratio of linear polymers versus crosslinker and the length of the linear polymer are varied, thus delivering a library of compositionally defined mucin-inspired constructs. Their viscoelastic properties are determined by frequency sweeps at 25 and 37 °C and compared to the corresponding behavior of native human mucus. Here, MIHs composed of a 10:1 ratio of LPG(SH)₂ and ETTMP 1300 are proved to be the best comparable to human airway mucus rheology.

Corannulene: A Curved Polyarene Building Block for the Construction of Functional Materials

This Account describes a body of research in the design and synthesis of molecular materials prepared from corannulene. Corannulene (C₂₀H₁₀) is a molecular bowl of carbon that can be visualized as the hydrogen-terminated cap of buckminsterfullerene. Due to this structural resemblance, it is often referred to as a buckybowl. The bowl can invert, accept electrons, and form host-guest complexes. Due to these characteristics, corannulene presents a useful building block in materials chemistry.In macromolecular science, for example, assembly of amphiphilic copolymers carrying a hydrophobic corannulene block enables micelle formation in water. Such micellar nanostructures can host large amounts of fullerenes (C₆₀ and C₇₀) in their corannulene-rich core through complementarity of the curved π-surfaces. Covalent stabilization of the assembled structures then leads to the formation of robust water-soluble fullerene nanoparticles. Alternatively, use of corannulene in a polymer backbone allows for the preparation of electronic and redox-active materials. Finally, a corannulene core enables polymer chains to respond to solution temperature changes and form macroscopic fibrillar structures. In this way, the corannulene motif brings a variety of properties to the polymeric materials.In the design of non-fullerene electron acceptors, corannulene is emerging as a promising aromatic scaffold. In this regard, placement of sulfur atoms along the rim can cause an anodic shift in the molecular reduction potential. Oxidation of the sulfur atoms can further enhance this shift. Thus, a variation in the number, placement, and oxidation state of the sulfur atoms can create electron acceptors of tunable and high strengths. An advantage of this molecular design is that material solubility can also be tuned. For example, water-soluble electron acceptors can be created and are shown to improve the moisture resistance of perovskite solar cells.Host-guest complexation between corannulene and γ-cyclodextrin under flow conditions of a microfluidic chamber allows for the preparation of water-soluble nanoparticles. Due to an oligosaccharide-based sugarcoat, the nanoparticles are biocompatible while the corannulene component renders them active toward nonlinear absorption and emission properties. Together, these attributes allow the nanoparticles to be used as two-photon imaging probes in cancer cells.Finally, aromatic extension of the corannulene nucleus is seen as a potential route to nonplanar nanographenes. Typically, such endeavors rely upon gas-phase synthesis or metal-catalyzed coupling protocols. Recently, two new approaches have been established in this regard. Photochemically induced oxidative cyclization, the Mallory reaction, is shown to be a general method to access corannulenes with an extended π-framework. Alternatively, solid-state ball milling can achieve this goal in a highly efficient manner. These new protocols bring practicality and sustainability to the rapidly growing area of corannulene-based nanographenes.In essence, corannulene presents a unique building block in the construction of functional materials. In this Account, we trace our own efforts in the field and point toward the challenges and future prospects of this area of research.

Disaggregation of a sumanene-containing fluorescent probe towards highly sensitive and specific detection of caesium cations

A sumanene derivative functionalized with triphenylbenzene units was found to exhibit aggregation-induced emission enhancement (AIEE). A disaggregation process after the addition of caesium cations (Cs+) was observed. This feature was employed for the design of the first sumanene-containing disaggregation-based fluorescent probe for specific, efficient and fast Cs+ recognition.

Corannulene Chalcogenides

The introduction of chalcogen atoms into a polycyclic aromatic hydrocarbon structure is an established method to tune material properties. In the context of corannulene (C₂₀ H₁₀ ), a fragment of fullerene C₆₀ , such structural adjustments have given rise to an emerging class of functional and responsive molecular materials. In this minireview, our aim is to discuss the synthesis and properties of such chalcogen (sulfur, selenium, and tellurium) derivatives of corannulene.

Flat corannulene: when a transition state becomes a stable molecule

Flat corannulene has been considered so far only as a transition state of the bowl-to-bowl inversion process. This study was driven by the prediction that substituents with strong steric repulsion could destabilize the bowl-shaped conformation of this molecule to such an extent that the highly unstable planar geometry would become an isolable molecule. To examine the substituents' effect on the corannulene bowl depth, optimized structures for the highly-congested decakis(t-butylsulfido)corannulene were calculated. The computations, performed with both the M06-2X/def2-TZVP and the B3LYP/def2-TZVP methods (the latter with and without Grimme's D3 dispersion correction), predict that this molecule can achieve two minimum structures: a flat carbon framework and a bowl-shaped structure, which are very close in energy. This rather unusual compound was easily synthesized from decachlorocorannulene under mild reaction conditions, and X-ray crystallographic studies gave similar results to the theoretical predictions. This compound crystallized in two different polymorphs, one exhibiting a completely flat corannulene core and the other having a bowl-shaped conformation.

Selenium and Tellurium Derivatives of Corannulene: Serendipitous Discovery of a One-Dimensional Stereoregular Coordination Polymer Crystal Based on Te-O Backbone and Side-Chain Aromatic Array

Monobromo-, tetrabromo-, and pentachloro-corannulene are subjected to nucleophilic substitution reactions with tolyl selenide and phenyl telluride-based nucleophiles generated in situ from the corresponding dichalcogenides. In the case of selenium nucleophile, the reaction provides moderate yields (52-77 %) of the targeted corannulene selenoethers. A subsequent oxidation of the selenium atoms proceeds smoothly to furnish corannulene selenones in 81-93 % yield. In the case of tellurides, only monosubstitution of the corannulene scaffold could be achieved albeit with concomitant oxidation of the tellerium atom. Unexpectedly, this monotelluroxide derivative of corannulene (RR'Te=O, R=Ph, R'=corannulene) is observed to form a linear coordination polymer chain in the crystalline state. In this chain, Te-O constitutes the polymer backbone around which the aromatic groups (R and R') arrange as polymer side-chains. The polymer crystal is stabilized through intramolecular π-π stacking interactions of the side-chains and intermolecular hydrogen and halogen bonding interactions with the solvent (chloroform) molecules. Interestingly, each diad of the polymer chain is racemic. Therefore, in terms of stereoregularity, the polymer chain can be described as syndiotactic.

Comparative toxicity analysis of corannulene and benzo[a]pyrene in mice

Increasing production of corannulene (COR), a non-planar polycyclic aromatic hydrocarbon (PAH) with promising applications in many fields, has raised a concern about its potential toxic effects. However, no study has been undertaken to evaluate its metabolism and toxicity in mammals. In this study, the acute toxicities of COR in mice were compared with benzo[apyrene (BaP), a typical planar PAH with almost the same molecular weight. After 3-day exposures, the concentrations of COR in both plasma and tissues of mice were higher than that of BaP. However, blood chemistry and tissue weight monitoring showed no observable toxicities in COR-exposed mice. Compared to BaP, exposure to COR resulted in less activation of the aryl hydrocarbon receptor (AhR) and thus less induction of hepatic cytochrome P450 1A(CYP1A) enzymes, which play a critical role in metabolism of both COR and BaP. Additionally, COR also elicited less oxidative stress and microbiota alteration in the intestine than did BaP. RNA-seq analysis revealed that liver transcriptomes are responsive to COR and BaP, with less alterations observed in COR-exposed mice. Unlike BaP, exposure to COR had no effects on hepatic lipid and xenobiotic metabolism pathways. Nonetheless, COR appeared to alter the mRNA expressions of genes involved in carcinogenicity, oxidative stress, and immune-suppression. To conclude, this study for the first time unveils a comparative understanding of the acute toxic effects of COR to BaP in mice, and provides crucial insights into the future safety assessment of COR.

Synthesis and optical properties of mono- and diaminocorannulenes

A simple synthesis of aminocorannulenes leads to the discovery of surprising properties: tunable visible emission; solid-state fluorescence; water-soluble fluorescent corannulenes.

Novel amphiphilic corannulene additive for moisture-resistant perovskite solar cells

Novel triethyleneglycol-functionalized corannulene sulfone (Cor-TEG) with by-design functionalities leads to favourable perovskite morphology, enhanced carrier extraction and protection against moisture.

Corannulenes with Electron-Withdrawing Substituents: Synthetic Approaches and Resulting Structural and Electronic Properties

Corannulene is a multifaceted polyaromatic compound. It has many interesting properties; for example, it has a bowl-shaped molecular structure that, in addition, undergoes a dynamic inversion process. It has attracted much attention within the last decades. This is not only due to its structural properties but also its electronic properties and its various potential applications to materials chemistry. Here, synthetic approaches towards corannulene derivatives with electron-withdrawing substituents are summarized. This includes both selective and unselective methods. Further, the electrochemical properties, that is, the reduction potentials, are analyzed and compared. As a main conclusion, one can state that the electron affinity depends roughly linearly on the number of substituents. Finally, the structural behavior of the substituted buckybowls in the solid state is highlighted. This also allows a general statement about the influence of the electronic and steric nature of substituents on the molecular structures and the solid-state packing of the corannulene derivatives.

Corannulene: a molecular bowl of carbon with multifaceted properties and diverse applications

The chemistry, properties and applications of corannulene are discussed.

Amphiphilic Corannulene Derivatives: Synthetic Access and Development of a Structure/Property Relationship in Thermoresponsive Buckybowl Amphiphiles

Eight new derivatives of corannulene have been synthesized, characterized, and examined for their water solubility and thermally triggered assembly behavior. To achieve this, the hydrophobic corannulene core was attached to the hydrophilic polyethylene glycol arm(s). Here, the substitution pattern as well as the arm length was varied systematically. Furthermore, the hydrophobic/hydrophilic ratio was adjusted by incorporating a phenyl ring at the junction point of the two moieties. A properties study revealed that a proper balance among the number, length, and chemical nature of the arm was required to ensure water solubility and thermoresponsive character. Remarkably, the lower critical solution temperature could be modulated within the range of 30-50 °C simply through adjusting the molecular structure of the assembling building block. This work, therefore, demonstrates synthetic feasibility of a wide range of amphiphilic corannulene derivatives and opportunity for modulation of their thermoresponsive behavior.