Substitution of bridge carbons for sulphur in calix[4]arene-bis-α-hydroxymethylphosphonic acid transformed mobile carrier into ionic channel accompanied with evoked muscle contraction and impaired neurotransmission powered by membrane action of resulting thiocalix[4]arene-bis-α-hydroxymethylphosphonic acid

The action of calix[4]arenes C-424, C-425 and C-1193 has been investigated on suspended cholesterol/egg phosphatidylcholine lipid bilayer in a voltage-clamp mode. Comparative analysis with the membrane action by calix[4]arene-bis-α-hydroxymethylphosphonic acid (C-99) has shown that the substitution of bridge carbons for sulphur and addition of another methyl group to two alkyl tales in the lower rim of former dipropoxycalix[4]arene C-99 transformed mobile carrier that C-99 created in lipid bilayer (Shatursky et al., 2014) into a transmembrane pore as exposure of the bilayer membrane to sulphur-containing derivative dibutoxythiocalix[4]arene C-1193 resulted in microscopic transmembrane current patterns indicative of a channel-like mode of facilitated diffusion. Within all calix[4]arenes tested a net steady-state voltage-dependent transmembrane current was readily achieved only after addition of calix[4]-arene C-1193. In comparison with the membrane action of C-99 the current induced by calix[4]-arene C-1193 exhibited a much weakened anion selectivity passing slightly more current at positive potentials applied from the side of bilayer membrane to which the calix[4]-arene was added. Testing C-1193 for the membrane action against smooth muscle cells of rat uterus or swine myometrium and synaptosomes of rat brain nerve terminals revealed an increase in intracellular concentration of Ca2+ with reduction of the effective hydrodynamic diameter of the smooth muscle cells and enhanced basal extracellular level of neurotransmitters (glutamate and γ-aminobutyric acid) after C-1193-induced depolarization of the nerve terminals.

Express assessment of neurotoxicity of particles of planetary and interstellar dust

Establishment of high-quality, consistent on-board assessment of the neurotoxicity of planetary, and interstellar dust particles will be required to predict their potential threat to human health during long-term space missions. This Perspective article proposes an approach for the rapid assessment of potential neurotoxicity of micro-sized and nano-sized dust particles based on experimental results with other neurotoxic particles. Capacity of particles to affect membrane potential, integrity of nerve terminals, and consequently key synaptic transmission characteristics can be assessed using a planar lipid bilayer technique by monitoring artificial membrane conductivity in the presence of particles. Preliminary neurotoxicity data of nanoparticles, including lunar and Martian dust simulants, obtained using a planar lipid bilayer technique, is compared with that acquired using more-established methodological approaches. Under space flight conditions, neurotoxicity assessments of particulate matter could be rapidly and reproducibly performed using a planar lipid bilayer technique, which does not require biological material.

Pyrrole N-H Anion Complexes

Synthetic pyrrole-based anion receptors date back to the 1990s. They have been extensively developed in the context of macrocyclic systems as expanded porphyrins and calixpyrroles, and related systems. The chemistry of open-chain pyrrolic systems is, in many respects, no less venerable. It also has more direct analogy to naturally occurring pyrrole-based anion binding motifs. However, it has not been the subject of a comprehensive review. Presented herein is a summary of efforts devoted to the creation of de novo pyrrole-based receptors, as well as the anion recognition chemistry of naturally occurring pyrrolic systems as prodigiosins and their synthetic analogues.

Thiacalix[4]arene-functionalized vesicles as phosphorescent indicators for pyridoxine detection in aqueous solution

Luminescent DPPC vesicles, decorated by new amphiphilic tetracarboxylate derivatives ofp-tert-butylthiacalix[4]arene with Tb(iii) were used for the selective detection of pyridoxine hydrochloride.