Molecularly Mixed Composite Membranes for Gas Separation Based on Macrocycles Embedded in a Polyimide

Polyimides are a polymer class that has been extensively investigated as a membrane material for gas separation owing to its interesting permselective properties in a wide range of operation temperatures and pressures. In order to improve their properties, the addition of different filler types is currently studied. p-tert-Butylcalix[n]arene macrocycles (PTBCs) with different cavity sizes (PTBC4, PTBC6, PTBC8) were used as fillers in a commercial thermoplastic polyimide, with a concentration in the range 1-9 wt%, to develop nanocomposite membranes for gas separation. The selected macrocycles are attractive organic compounds owing to their porous structure and affinity with organic polymers. The nanocomposite membranes were prepared in the form of films in which the polymeric matrix is a continuous phase incorporating the dispersed additives. The preparation was carried out according to a pre-mixing approach in a mutual solvent, and the solution casting was followed by a controlled solvent evaporation. The films were characterized by investigating their miscibility, morphology, thermal and spectral properties. The gas transport through these films was examined as a function of the temperature and also time. The results evidenced that the incorporation of the chosen nanoporous fillers can be exploited to enhance molecular transport, offering additional pathways and promoting rearrangements of the polymeric chains.

Effects of the Calix[4]arene Derivative Compound OTX008 on High Glucose-Stimulated ARPE-19 Cells: Focus on Galectin-1/TGF-β/EMT Pathway

Diabetic retinopathy (DR) is a neurovascular disease characterized by the reduction of retina integrity and functionality, as a consequence of retinal pigment epithelial cell fibrosis. Although galectin-1 (a glycan-binding protein) has been associated with dysregulated retinal angiogenesis, no evidence has been reported about galectin-1 roles in DR-induced fibrosis. ARPE-19 cells were cultured in normal (5 mM) or high glucose (35 mM) for 3 days, then exposed to the selective galectin-1 inhibitor OTX008 (2.5–5–10 μM) for 6 days. The determination of cell viability and ROS content along with the analysis of specific proteins (by immunocytochemistry, Western blotting, and ELISA) or mRNAs (by real time-PCR) were performed. OTX008 5 μM and 10 μM improved cell viability and markedly reduced galectin-1 protein expression in cells exposed to high glucose. This was paralleled by a down-regulation of the TGF-β/, NF-kB p65 levels, and ROS content. Moreover, epithelial–mesenchymal transition markers were reduced by OTX008 5 μM and 10 μM. The inhibition of galectin-1 by OTX008 in DR may preserve retinal pigment epithelial cell integrity and functionality by reducing their pro-fibrotic phenotype and epithelial–mesenchymal transition phenomenon induced by diabetes.

Expanding the Chemical Space of Biocompatible Fluorophores: Nanohoops in Cells

The design and optimization of fluorescent molecules has driven the ability to interrogate complex biological events in real time. Notably, most advances in bioimaging fluorophores are based on optimization of core structures that have been known for over a century. Recently, new synthetic methods have resulted in an explosion of nonplanar conjugated macrocyclic molecules with unique optical properties yet to be harnessed in a biological context. Herein we report the synthesis of the first aqueous-soluble carbon nanohoop (i.e., a macrocyclic slice of a carbon nanotube prepared via organic synthesis) and demonstrate its bioimaging capabilities in live cells. Moreover, we illustrate that these scaffolds can be easily modified by well-established "click" chemistry to enable targeted live cell imaging. This work establishes the nanohoops as an exciting new class of macrocyclic fluorophores poised for further development as novel bioimaging tools.

Inclusion Complexes of a New Family of Non-Ionic Amphiphilic Dendrocalix[4]arene and Poorly Water-Soluble Drugs Naproxen and Ibuprofen

The inclusion complexes of a new family of nonionic amphiphilic calix[4]arenes with the anti-inflammatory hydrophobic drugs naproxen (NAP) and ibuprofen (IBP) were investigated. The effects of the alkyl chain’s length and the inner core of calix[4]arenes on the interaction of the two drugs with the calix[4]arenes were explored. The inclusion complexes of Amphiphiles 1a–c with NAP and IBP increased the solubility of these drugs in aqueous media. The interaction of 1a–c with the drugs in aqueous media was investigated through fluorescence, molecular modeling, and ¹H-NMR analysis. TEM studies further supported the formation of inclusion complexes. The length of lipophilic alkyl chains and the intrinsic cyclic nature of cailx[4]arene derivatives 1a–c were found to have a significant impact on the solubility of NAP and IBP in pure water.

Potential Eye Drop Based on a Calix[4]arene Nanoassembly for Curcumin Delivery: Enhanced Drug Solubility, Stability, and Anti-Inflammatory Effect

Curcumin is an Indian spice with a wide spectrum of biological and pharmacological activities but poor aqueous solubility, rapid degradation, and low bioavailability that affect medical benefits. To overcome these limits in ophthalmic application, curcumin was entrapped in a polycationic calix[4]arene-based nanoaggregate by a simple and reproducible method. The calix[4]arene-curcumin supramolecular assembly (Calix-Cur) appeared as a clear colloidal solution consisting in micellar nanoaggregates with size, polydispersity index, surface potential, and drug loading percentage meeting the requirements for an ocular drug delivery system. The encapsulation in the calix[4]arene nanoassembly markedly enhanced the solubility, reduced the degradation, and improved the anti-inflammatory effects of curcumin compared to free curcumin in both in vitro and in vivo experiments. Calix-Cur did not compromise the viability of J774A.1 macrophages and suppressed pro-inflammatory marker expression in J774A.1 macrophages subjected to LPS-induced oxidative stress. Histological and immunohistochemical analyses showed that Calix-Cur reduced signs of inflammation in a rat model of LPS-induced uveitis when topically administrated in the eyes. Overall, the results supported the calix[4]arene nanoassembly as a promising nanocarrier for delivering curcumin to anterior ocular tissues.

A water-soluble pillar[5]arene as a new carrier for an old drug

The ability of deca-carboxylatopillar[5]areneWP5to bind the antibiotic amikacin and modulate its antimicrobial response towards Gram-positive bacteria is reported.

Supramolecular activation of the photodynamic properties of porphyrinoid photosensitizers by calix[4]arene nanoassemblies

Micellar-like nanocontainers of an amphiphilic calix[4]arene switch on the capability of porphyrinoid photosensitizers to photogenerate singlet oxygen and kill bacteria.

Self-assembly of amphiphilic anionic calix[4]arenes and encapsulation of poorly soluble naproxen and flurbiprofen

The ability of an anionic calix[4]arene amphiphile to aggregate and to solubilize, as a result, the poorly water-soluble drugs naproxen and flurbiprofen is described.

Design and synthesis of a multivalent fluorescent folate–calix[4]arene conjugate: cancer cell penetration and intracellular localization

Fluorescent multivalent folate–calix[4]arene–NBD selectively penetrates cancer cellsviafolate receptor-mediated endocytosis and localizes in endo-lysosomes.

"Click and go": simple and fast folic acid conjugation

Folic acid targeting by functionalization of the terminal γ-carboxylic acid is one of the most important strategies to selectively deliver chemotherapeutics and dyes to cancer cells which overexpress folate receptors. However, conjugation of folic acid is limited by its unique solubility and by selectivity issues imposing the need for expensive preparative reverse-phase chromatographic purification to isolate γ-folate conjugates. Herein is provided a novel synthetic tool for the synthesis of new folic acid conjugates with excellent γ-purity based on strain-promoted alkyne-azide cycloadditions with a γ-folate-cyclooctyne conjugate 3. To demonstrate the potential of this methodology several new folate conjugates were synthesized with high γ-purity and without using any type of chromatographic purification by reacting conjugate 3 with several fluorescent probes, polymers and siliceous materials bearing azide. In addition, the cycloaddition reaction between conjugate 3 and an azido-derived fluorescent dye was successfully performed in cellular media leading to an increase of fluorescence in the cells which overexpress folate receptors (NCI-H460).