Diclofenac sodium aqueous systems at low concentrations: Interconnection between physicochemical properties and action on hydrobionts.

Diclofenac sodium (DS) is a widely used nonsteroidal anti-inflammatory drug (NSAIDs). NSAIDs are poorly removed during standard wastewater treatment. The consequences of the presence of NSAIDs in rivers and lakes at 10-11-10-8 mol/L are not yet established; therefore, ecotoxicologists have focused their efforts on studying the effect of low-concentration NSAIDs on fish and hydrobionts, and also on predicting the potential risks to humans. Literature provides some information about the bioeffects of some NSAID solutions in low concentrations but there is no physicochemical explanation for these phenomena. Studying the physicochemical patterns of DS solutions in the low range of concentrations and establishing an interconnection between the solutions' physicochemical properties and bioeffects can provide a conceptually new and important source of information regarding the unknown effects of DS. The physicochemical properties and action of DS solutions on Ceriodaphnia affinis cladocerans, Paramecium caudatum infusoria, Chlorella vulgaris unicellular green algae, as well as on the growth of the roots of Triticum vulgare wheat seeds, were studied in the calculated concentration range of 1 × 10-3-1 × 10-18 mol/L. The relationship between these phenomena was established using the certified procedures for monitoring the toxicity of natural water and wastewater. It was shown for the first time that water solutions of DS are dispersed systems in which the dispersed phase undergoes a rearrangement with dilution, accompanied by changes in its size and properties, which affects the nonmonotonic dependences of the system's physicochemical properties and could cause nonmonotonic changes in action on hydrobionts in the low concentration range.

Nanoconjugates of a calixresorcinarene derivative with methoxy poly(ethylene glycol) fragments for drug encapsulation.

In order to obtain a non-toxic amphiphilic calixresorcinarene capable to form nanoconjugates for drug encapsulation, tetraundecylcalixresorcinarene functionalized by methoxy poly(ethylene glycol) chains has been synthesized. The macrocycle obtained is characterized by low hemotoxicity. In aqueous solution it forms nanoassociates that are able to encapsulate organic substrates of different hydrophobicity, including drugs (doxorubicin, naproxen, ibuprofen, quercetin). The micelles of the macrocycle slowed down the release of the hydrophilic substrates in vitro. In physiological sodium chloride solution and phosphate-buffered saline, the micelles of the macrocycle acquire thermoresponsive properties and exhibit a temperature-controlled release of doxorubicin in vitro. The combination of the low toxicity and the encapsulation properties of the obtained calixresorcinarene-mPEG conjugate shows promising potential for the use as a supramolecular drug-delivery system.

Closed polymer containers based on phenylboronic esters of resorcinarenes.

Novel polymer nanospheres (p(SRA-B)) were prepared by cross-linking a sulfonated resorcinarene (SRA) with phenylboronic acid. p(SRA-B) shows good stability in water and can be used as a nanocontainer for the pH- and glucose-controlled substrate release. Fluorescent dyes (fluorescein, pyrene and 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt) were successfully loaded into p(SRA-B). The release of dye is achieved by lowering the pH value to 3 or by adding glucose.

High catalytic activity of palladium nanoparticle clusters supported on a spherical polymer network.

In this communication we report the synthesis of Pd nanoparticle clusters achieved via the assembly of Pd nanoparticles on the surface of a spherical polymer network. The network exhibits flexibility and adapts to the cluster formation. The nanoclusters display high catalytic activity toward p-nitrophenol reduction and the Suzuki-Miyaura coupling reaction.

Tb(III)-doped silica nanoparticles for sensing: effect of interfacial interactions on substrate-induced luminescent response.

The present work introduces the easy modification of the water-in-oil microemulsion procedure aimed at the doping of the Tb(III) complexes within core or shell zones of the silica nanoparticles (SNs), which are designated as "core-shell", "shell", and "core". The dye molecules, chelating ligands, and copper ions were applied as the quenchers of Tb(III)-centered luminescence through dynamic or/and static mechanisms. The binding of the quenchers at the silica/water interface results in the quenching of the Tb(III) complexes within SNs, which, in turn, is greatly dependent on the synthetic procedure. The luminescence of "core" SNs remains unchanged under the binding of the quenchers at the silica/water interface. The quenching through dynamic mechanism is more significant for "core-shell" and "shell" than for "core" SNs. Thus, both "core-shell" and "shell" SNs have enough percentage of the Tb(III) complexes located close to the interface for efficient quenching through the energy transfer. The quenching through the ion or ligand exchange is most efficient for "core-shell" SNs due to the greatest percentage of the Tb(III) complexes at the silica/water interface, which correlates with the used synthetic procedure. The highlighted regularities introduce the applicability of "core-shell" SNs used as silica beads for phosphatidylcholine bilayers in sensing their permeability toward the quenching ions.

Langmuir monolayers and thin films of amphifilic thiacalix[4]arenes. Properties and matrix for the immobilization of cytochrome c.

Formation and properties of Langmuir films of thiacalix[4]arene (TCA) derivatives containing N-donor groups on the lower rim (Y═O(CH2)3CN; OCH2CN; NH2; OCH2ArCN-p) in 1,3-alternate conformation on aqueous subphase and solid substrates have been studied. Only tetra-cyanopropoxy-p-tert-butylthiacalix[4]arene 1 forms a typical monomolecular layer with perpendicular orientation of the macrocycle relative to the water-air interface that is able to immobilize cytochrome c in the entire range of the surface pressure. Obtained monolayers were transferred by Langmuir-Schaefer technique onto quartz, indium-tin oxide (ITO), and silicon. It was demonstrated that protein activity is retained after immobilization on the substrate.

Controlling the size and morphology of supramolecular assemblies of viologen-resorcin[4]arene cavitands.

A novel class of self-assembling nanoparticles is formed with viologen-resorcin[4]arene cavitands; the association model is strongly controlled by their hydrophobicity. Interestingly, the cavitand assemblies are designed through click chemistry to form self-assembled noncovalently connected aggregates through counterion displacement. The iodide and benzoate ions are utilized as strongly polarizable counterions to induce cavitand self-assembly. The counterion-mediated decrease in hydrophilicity of the viologen-resorcin[4]arenes is the underlying trigger to induce particle formation. These particles can be used as nanocontainers and find their applications in delivery systems.

Changes in permittivity and density of molecular liquids under high pressure.

We collected and analyzed the density and permittivity of 57 nonpolar and dipolar molecular liquids at different temperatures (143 sets) and pressures (555 sets). No equation was found that could accurately predict the change to polar liquid permittivity by the change of its density in the range of the pressures and temperatures tested. Consequently, the influence of high hydrostatic pressure and temperature on liquid permittivity may be a more complicated process compared to density changes. The pressure and temperature coefficients of permittivity can be drastically larger than the pressure and temperature coefficients of density, indicating that pressure and particularly temperature significantly affect the structure of molecular liquids. These changes have less influence on the density change but can strongly affect the permittivity change. The clear relationship between the tangent and secant moduli of the permittivity curvatures under pressure for various molecular liquids at different temperatures was obtained, from which one can calculate the Tait equation coefficients from the experimental values of the pressure influence on the permittivity at ambient pressure.

Design of supramolecular biomimetic catalysts of high substrate specificity by noncovalent self-assembly of calix[4]arenes with amphiphilic and polymeric amines.

Supramolecular biomimetic catalysts of high substrate specificity are developed based on amphiphilic oxyethylated calix[4]arene bearing iso-nonyl fragments at the upper rim and hexadeca(ethylene glycol) fragments at lower rim (9CO16), and amines of amphiphilic or polymeric nature. Two critical concentrations determined by tensiometry and dye solubilization methods are probably reflect the onset of association process and transition from bimodal to monomodal size distribution revealed by the dynamic light scattering method. Amine components used may form aggregates as well, which is mediated by hydrophobic effect due to occurrence of long-chain alkyl tails. The micellar rate effect of the designed systems toward the cleavage of carboxylic acid ester is shown to be contributed by the formation of mixed aggregates with the reactive functional groups, as well as by the pKa shift of the amine and the character of the distribution of reagents in functional micelles. In the case of long-chain primary amines, an inversion of micellar rate effect (catalysis to inhibition) occurs upon transferring from the less hydrophobic substrate, p-nitrophenyl acetate, to the more hydrophobic analogs, p-nitrophenyl laurate and p-nitrophenyl caprinate. The opposite effect (inhibition of the reaction of p-nitrophenyl acetate and the acceleration of the process of hydrophobic analogs) was observed in systems based on polyethyleneimine.

The energy transfer based fluorescent approach to detect the formation of silica supported phosphatidylcholine and phosphatidylserine containing bilayers.

The work introduces the quenching of silica coated Tb(III) complexes by merocyanine 540 (MC540) and copper ions as a tool to reveal the adsorption of phosphatidylcholine (PC) and phosphatidylserine (PS) at various PS:PC ratio onto silica nanoparticles doped with Tb(III) complex. The binding of MC540 with PC-based bilayers and copper ions with PS-based ones are the basis of their use as organic and inorganic probes to sense PS:PC ratio in silica supported mixed bilayers. The enrichment of mixed bilayers by PS results in the displacement of MC540 anions, while it enhances the binding with copper ions. The displacement or binding of probe ions results in the diverse luminescence response of Tb(III)-centred luminescence. The reestablishment of the steady state and time resolved luminescence is observed, when MC540 anions are applied as probes. The use of copper ions as probes results in the opposite quenching effect. The developed route enables to discriminate the formation of the phospholipids bilayers onto silica surface from those in the bulk of solution under various concentration conditions.

Supramolecular design of biocompatible nanocontainers based on amphiphilic derivatives of a natural compound isosteviol.

Two diterpenoid surfactants with ammonium head groups and bromide (S1) or tosylate (S2) counterions have been synthesized. Exploration of these biomimetic species made it possible to demonstrate that even minor structural changes beyond their chemical nature may dramatically affect their solution behavior. While their aggregation thresholds differ inconsiderably, morphological behavior and affinity to lipid bilayer are strongly dependent on the counterion nature. Compound S2 demonstrates properties of typical surfactants and forms small micelle-like aggregates above critical micelle concentration. For surfactant S1, two critical concentrations and two types of aggregates occur. Structural transitions have been observed between small micelles and aggregates with higher aggregation numbers and hydrodynamic diameter of ca. 150 nm. Unlike S2, surfactant S1 is shown to integrate with liposomes based on dipalmitoylphosphatidylcholine, resulting in a decrease of the temperature of the main phase transition. Both surfactants demonstrate an effective complexation capacity toward oligonucleotide (ONu), which is supported by recharging the surfactant-ONu complexes and the ethidium bromide exclusion at a low N/P ratio. Meanwhile, a very weak complexation of plasmid DNA with the surfactants has been revealed in the gel electrophoresis experiment. The DNA transfer to bacterial cells mediated by the surfactant S1 is shown to depend on the protocol used. In the case of the electroporation, the inhibition of the cell transformation occurs in the presence of the surfactant, while upon the chemical treatment no surfactant effect has been observed. The variability in the morphology, the biocompatibility, the nanoscale dimension and the high binding capacity toward the DNA decamer make it possible to nominate the designed surfactants as promising carriers for biosubstrates or as a helper surfactant for the mixed liposome-surfactant nanocontainers.

Tunable biomimetic systems based on a novel amphiphilic pyrimidinophane and a helper nonionic surfactant.

Tunable nanosystems based on a novel water insoluble pyrimidinic amphiphile are designed. pH dependent aggregates composed of protonated pyrimidinophane 1 are formed at pH<4, which undergo reversible transition to precipitate at neutral and basic conditions. The approach assuming the application of a helper nonionic surfactant Triton-X-100 (TX-100) is used in this work. Different models of a self-assembly were found depending on the molar ratio of components and solution pH. In the equimolar 1-TX-100 solution, mixed assemblies contributed by aggregated molecules of both TX-100 and cationic form of 1 are formed in acidic conditions. Upon alkalization, deprotonated pyrimidinophane molecules shift toward the micellar core. The assemblies undergo reversible precipitation after 4-5h, while the excess of TX-100 leads to the formation of highly stable mixed aggregates. The acidification-alkalization cycles followed by the aggregation/precipitation and the re-charging of aggregates can be multiply repeated. Surprisingly, stable mixed aggregates are also formed under the excess of pyrimidinophane in both the acidic and alkaline conditions, but at a certain component ratio. They are characterized by the highest micellization degree among all the systems studied. The low concentration threshold of these assemblies in alkali solution is probably due to their nonionic character.

Crystal violet dye in complexes with amphiphilic anionic calix[4]resorcinarenes: binding by aggregates and individual molecules.

Here, we report on a systematic study of six calix[4]resorcinarene macrocycles bearing eight carboxylic groups on the upper rim and four different lower rim substituents that are either aliphatic (2, 4, and 5) or alkylaromatic (1, 3, and 6). The macrocycles were studied in their individual aqueous solutions and in the presence of triphenylmethane dye crystal violet. It was found that binding of crystal violet with aggregated macrocycles shields it from the bulk of solution, preventing its discoloration under basic conditions and electrochemical reduction on the glassy carbon electrode. Most efficient shielding, reducing the rate of discoloration more than 173 times, as compared to solution with no macrocycle, was achieved with 6 forming aggregates of average 72 molecules in 0.1 mM solutions.

Novel biomimetic systems based on amphiphilic compounds with a diterpenoid fragment: role of counterions in self-assembly.

Novel biomimetic systems are designed based on cationic surfactants composed of an isosteviol moiety and different counterions, namely bromide (S1) and tosylate (S2). The counterion structure is shown to play a crucial role in the surfactant association. A number of methods used provide evidence that only one type of aggregate, i.e., micelles are observed in the S2 systems, while a concentration-dependent association occurs in the case of S1. The DLS and fluorescence anisotropy measurements reveal that the micelle-vesicle-micelle transitions probably occur with the S1 system. The occurrence of small aggregates near the critical micelle concentration with radii of 2.5 nm is supported by NMR self-diffusion data. The Orange OT solubilization results strongly support the idea of a second threshold in the S1 system around 0.025 mM and provide evidence that hydrophobic domains occur in the aggregates. The latter property and the capacity to integrate with the lipid bilayer make it possible to suggest the newly synthesized surfactants as effective nanocontainers for hydrophobic guests.

The discrimination between phospholipids of diverse structure and phosphacoumarins of various hydrophobicity through fluorescent response of Tb-doped silica nanoparticles decorated by cationic surfactant.

The work represents colloids of silica nanoparticles displaying fluorescent response on biorelevant compounds exemplified by phosphacoumarins and phospholipids. The luminescent properties of the colloids arise from Tb(III) complexes doped into silica nanoparticles (SNs). The noncovalent decoration of SNs by dicationic surfactant with further interfacial binding of dye anions enables to develop colloids programmed to display a substrate induced fluorescent response. The latter results from the quenching of Tb(III) centered luminescence by dye anions through dynamic mechanism and subsequent displacement of quenching anions by the non-quenching substrates from the interface of SNs. Both negative charge and hydrophobicity of substrates are the key factors affecting the selectivity of the substrate induced fluorescent response. The peculiar effects of zwitter-ionic and anionic phospholipids on the fluorescent response have been revealed. The applicability of the fluorescent procedure in the sensing of impurities in commercial phosphatidylcholine is also introduced.

The interfacial interactions of Tb-doped silica nanoparticles with surfactants and phospholipids revealed through the fluorescent response.

The quenching effect of dyes (phenol red and bromothymol blue) on Tb(III)-centered luminescence enables to sense the aggregation of cationic and anionic surfactants near the silica surface of Tb-doped silica nanoparticles (SN) in aqueous solutions. The Tb-centered luminescence of non-decorated SNs is diminished by the inner filter effect of both dyes. The decoration of the silica surface by cationic surfactants induces the quenching through the energy transfer between silica coated Tb(III) complexes and dye anions inserted into surfactant aggregates. Thus the distribution of surfactants aggregates at the silica/water interface and in the bulk of solution greatly affects dynamic quenching efficiency. The displacement of dye anions from the interfacial surfactant adlayer by anionic surfactants and phospholipids is accompanied by the "off-on" switching of Tb(III)-centered luminescence.

Guest controlled aggregation of amphiphilic sulfonatomethylated calix[4]resorcinarenes in aqueous solutions.

Supramolecular nanoaggregates formed through the association of amphiphilic sulfonatomethylated calix[4]resorcinarenes with different substituents on the lower rim (methyl, pentyl, heptyl) and number of aromatic, aliphatic, and cationic guests differing in their shapes and sizes were investigated in aqueous solution by various NMR techniques ((1)H, 2D NOESY, FT-PGSE). It was shown that slight variations of the alkyl chain length on the lower rim of calixresorcinarenes dramatically change their aggregation behavior. Unlike the other calixresorcinarenes studied, the "head-to-tail" packing mode is observed for calixresorcinarene with pentyl moieties on the lower rim, which is unusual for amphiphilic calixarene aggregates. This calixresorcinarene demonstrates the stronger binding capacity toward the guest molecules due to their encapsulation into the capsule-like aggregate subunits. The guest-host complexation modifies the properties of both components, with the size of the resulted colloid particles being controlled by the guest nature.

Self-assembling systems based on amphiphilic alkyltriphenylphosphonium bromides: elucidation of the role of head group.

A systematic study of the aggregation behavior of alkyltriphenylphosphonium bromides (TPPB-n; n=8, 10, 12, 14, 16, 18; here n is the number of carbon atoms in alkyl groups) in aqueous solutions has been carried out and compared with trimethyl ammonium bromides (TMAB-n). Critical micelle concentrations (cmcs) of TPPB-n and TMAB-n decrease with the number of carbon atoms with the slope parameter of ca.0.3. The low cmcs and effective solubilization power toward Orange OT indicate high micellization capacity of phosphonium surfactants. The low counterion binding parameter ß is revealed for TPPB-10 and TPPB-12, while high counterion binding of ≥80% is observed for high TPPB-n homologs. Values of the surface potential ψ calculated on the basis of pK(a) shifts of p-nitrophenols is similar for both series and monotonously increase with alkyl chain length. Several points indicate non-monotonic changes within TPPB-n series. There are peculiarities of the tensiometry and solubilization plots for high homologs and above mentioned increases in counterion binding on transiting from low to high molecular weight surfactants. Differences in aggregation behavior between TPPB and TMAB series and between low and high homologs can be due to the specific structural character of the TPP(+) cation, which is supported by X-ray data.

Cascade and commutative self-assembles of nanoscale three-component systems controlled by the conformation of thiacalix[4]arene.

In this work, the formation of two- and three-component supramolecular systems based on cone, partial cone, 1,3-alternate stereoisomers of heteroditopic "hosts": p-tert-butylthiacalix[4]arene containing 4-amidopyridine fragments with silver(I) cations and dicarboxylic acids in liquid and solid phases were studied by UV spectroscopy, dynamic light scattering, and atomic force microscopy methods. It has been shown that these macrocycles are coreceptors, capable of simultaneously binding silver(I) cations, dicarboxylic acids (oxalic, malonic, succinic, maleic, fumaric acids), and hydroxyl acids (glycol, tartaric acids). For the first time, by the dynamic light scattering method, it has been shown that the conformation of p-tert-butyl thiacalix[4]arenes significantly affects the type of three-component system formed: cone is characterized by the formation of cascade systems; for partial cone, intermediate systems; and for the 1,3-alternate stereoisomers, three types of three-component systems (cascade, intermediate, and commutative) were observed.

Novel self-assembling system based on resorcinarene and cationic surfactant.

Mixed association of calix[4]resorcinarene with ethyl sulfonate groups on the lower rim and dimethylaminomethyl groups on the upper rim (CR) and cationic surfactant 4-aza-1-hexadecyl-azoniabicyclo[2.2.2]octane bromide (DABCO-16) is studied by methods of tensiometry, conductometry, potentiometry and NMR spectroscopy at fixed CR concentration and varied surfactant concentration. Beyond ca. 0.4 mM of DABCO-16, mixed aggregates enriched by CR are proved to be formed due to electrostatic forces, while beyond ca. 5 mM, aggregates enriched by surfactant occur due to the hydrophobic effect. Spectrophotometry monitoring of the solubilization of a hydrophobic dye, Orange OT, demonstrated that only the second type of mixed aggregate enriched by DABCO-16 is capable of binding the organic probe, while the mixed system where the surfactant is a minor component shows no binding capacity towards Orange OT. This finding can be used for the design of nanocontainers with controllable binding/release properties.