Darya A. Samarkina

Supramolecular systems based on dicationic pyrimidine-containing surfactants and polyethyleneimine

Aggregates based on a novel pyrimidine-containing amphiphile containing three uracil fragments were quantitatively characterized. The critical micelle concentration (CMC) is 2 mmol L–1 and the degree of binding of counterions is β = 0.95, which is consistent with the low zeta potential of the micelles equal to +5 mV. Aggregates with a diameter of 45 nm are formed in the CMC region, and in the region of higher concentrations the aggregates are rearranged to micelle-like particles. In the presence of hydrophilic polymer polyethyleneimine, the CMC significantly decreases (to 0.2 mmol L–1), the degree of binding of counterions decreases, and the electrokinetic potential increases. The size of the aggregates in the binary system is 6—7 nm.

Substrate specific nanoreactors based on pyrimidine-containing amphiphiles of various structures for cleavage of phosphonates

ABSTRACT The series of novel pyrimidine-containing amphiphiles were examined as catalysts for cleavage of phosphonates having various hydrophobicities. Kinetic data showed marked substrate specificity of three different types (i) inhibition for both substrates, (ii) catalysis for more hydrophobic phosphonate and inhibition for less hydrophobic phosphonate, and (iii) catalysis for both substrates. The highest acceleration (more than 11 times in comparison with the reaction in the absence of amphiphile) has been reached in the case of dicationic amphiphile with three hydrophobic tails. GRAPHICAL ABSTRACT

Erratum to: “Self-assembling catalytic systems based on new amphiphile containing purine fragment, exhibiting substrate specificity in hydrolysis of phosphorus acids esters”

ACKNOWLEDGMENTS should be as follows: This work was financially supported by the Russian Science Foundation (project no. 14-50-00014).

New amphiphilic multiheterocycle: Micelle-forming properties and effect on the reactivity of phosphorus acid esters

Supramolecular systems based on a novel tetracationic amphiphilic multiheterocycle have been studied by tensiometry, conductometry, pH-metry, spectrophotometry, and dynamic and electrophoretic light scattering. The critical micelle concentration of the system has been determined (0.4 mM), and the possibility of open and closed association models realization has been demonstrated. A high solubilizing ability of the aggregates toward hydrophobic guest species has been revealed. Micellar catalysts based on the new multiheterocycle have shown substrate specificity in the hydrolysis of phosphonates possessing different hydrophobicities.

Combination delivery of two oxime-loaded lipid nanoparticles: Time-dependent additive action for prolonged rat brain protection

&NA; A novel approach for brain protection against poisoning by organophosphorus agents is developed based on the combination treatment of dual delivery of two oximes. Pralidoxime chloride (2‐PAM) and a novel reactivator, 6‐(5‐(6,7‐dimethoxy‐3,4‐dihydroisoquinolin‐2(1H)‐yl)pentyl)‐3‐hydroxy picolinaldehyde oxime (3‐HPA), have been loaded in solid‐lipid nanoparticles (SLNs) to offer distinct release profile and systemic half‐life for both oximes. To increase the therapeutic time window of both oximes, SLNs with two different compartments were designed to load each respective drug. Oxime‐loaded SLNs of hydrodynamic diameter between 100 and 160 nm and negative zeta potential (−30 to −25 mV) were stable for a period of 10 months at 4 °C. SLNs displayed longer circulation time in the bloodstream compared to free 3‐HPA and free 2‐PAM. Oxime‐loaded SLNs were suitable for intravenous (iv) administration. Paraoxon‐poisoned rats (0.8 × LD50) were treated with 3‐HPA‐loaded SLNs and 2‐PAM+3‐HPA‐loaded SLNs at the dose of 3‐HPA and 2‐PAM of 5 mg/kg. Brain AChE reactivation up to 30% was slowly achieved in 5 h after administration of 3‐HPA‐SLNs. For combination therapy with two oximes, a time‐dependent additivity and increased reactivation up to 35% were observed. Graphical abstract Figure. No caption available.

Aggregation Capacity and Complexation Properties of a System Based on an Imidazole-Containing Amphiphile and Bovine Serum Albumin

A complex of physicochemical methods was used to study the aggregation characteristics of an imidazolium-containing amphiphile and its ability for complex formation with bovine serum albumin (BSA). Tensiometry showed that adding BSA to the surfactant decreases the aggregation threshold of the system by a factor of 50. Dynamic light scattering established, that the size of the surfactant–BSA complexes depends on the size of the polypeptide (6–10 nm) and is independent on the concentrations of the surfactant and BSA. The Stern‒Volmer constants and surfactant‒protein binding constants were calculated from fluorescence spectroscopy data.