Composite systems for medical purposes, created on the basis of hydrophobic silica

Composite systems with certain cytotoxic (AM1/lectin) and adsorption (AM1/gelatin) activity have been developed on the basis of methyl silica and protein molecules – lectin and gelatin. For both types of composites, mechanisms of water binding to the surface and methods of transferring of hydrophobic materials into the aquatic environment have been investigated. The state of interfacial water in air, organic and acid media was studied. It has been found that the presence of a hydrophobic component in composites stabilizes of surface water in a weakly associated state, when a significant part of water molecules does not form hydrogen bonds. Liquid hydrophobic medium enhances this effect, and the strong acid (trifluoroacetic), added to it, promotes the transition of water to a strongly associated state. It has been shown that the redistribution of water in the interparticle intervals of AM1 with protein molecules immobilized on their surface changes under the influence of mechanical loads. Mechanoactivated samples are characterized by the possibility of water penetration into the spaces between the primary particles of methyl silica. It has been shown that immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. If we analyze the changes in the distributions of radii R of the clusters of adsorbed water, we can state that in the water adsorbed by native lectin molecules, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates.

Physicochemical factors affecting the wettability of copper mine blasting dust

To investigate the factors affecting the wettability of copper mine blasting dust, the primary blasting dust was collected from an open-pit copper mine and separated into hydrophilic blasting dust (HLBD) and hydrophobic blasting dust (HBBD) using water flotation method. The physicochemical properties of HLBD and HBBD were measured and compared with each other. The properties included particle size distributions (PSDs), micromorphologies, pore structures, mineral components and surface organic carbon functional groups. The results show that particle size and pore structure of the blasting dust are the main factors affecting its wettability. Specifically, particle size of HBBD is smaller than that of HLBD, and their respiratory dust (less than 10 µm) accounts for 61.74 vol% and 53.00 vol%, respectively. The pore structure of HBBD is more developed, and the total pore volume of HBBD is 1.66 times larger than that of HLBD. The identical mineral compositions were detected in HLBD and HBBD by X-rays diffraction (XRD); however, the surface organic hydrophobic component of HBBD is slightly larger than that of HLBD, this may be the reason for the poor wettability of HBBD. This study is significant to understand the effects of physicochemical properties of copper mine blasting dust on its wettability.

Amphiphilic Molecular Brushes with Regular Polydimethylsiloxane Backbone and Poly-2-isopropyl-2-oxazoline Side Chains. 2. Self-Organization in Aqueous Solutions on Heating

The behavior of amphiphilic molecular brushes in aqueous solutions on heating was studied by light scattering and turbidimetry. The main chain of the graft copolymers was polydimethylsiloxane, and the side chains were thermosensitive poly-2-isopropyl-2-oxazoline. The studied samples differed in the length of the grafted chains (polymerization degrees were 14 and 30) and, accordingly, in the molar fraction of the hydrophobic backbone. The grafting density of both samples was 0.6. At low temperatures, macromolecules and aggregates, which formed due to the interaction of main chains, were observed in solutions. At moderate temperatures, heating solutions of the sample with short side chains led to aggregation due to dehydration of poly-2-isopropyl-2-oxazoline and the formation of intermolecular hydrogen bonds. In the case of the brush with long grafted chains, dehydration caused the formation of intramolecular hydrogen bonds and the compaction of molecules and aggregates. The lower critical solution temperature for solutions of the sample with long side chains was higher than LCST for the sample with short side chains. It was shown that the molar fraction of the hydrophobic component and the intramolecular density are the important factors determining the LCST behavior of amphiphilic molecular brushes in aqueous solutions.

Amphiphilic silica derivatives associated with oligomeric medium in octamethylcyclotetrasiloxane polymerization

The amphiphilic derivatives of silica associated with oligomeric medium have been studied as modifiers of the catalyst for the octamethylcyclotetrasiloxane polymerization of anionic nature. The effect of the modifiers structure on the polymerization time of the obtained polydimethylsiloxanes was investigated. It was found that the modifier, like the initial polyoxyethylene glycol, exhibits the properties of promoters for the catalytic polymerization of octamethylcyclotetrasiloxane by the anionic mechanism. To establish the role of amphiphilic silica derivatives in the occurrence of intermolecular interactions in polydimethylsiloxanes that were obtained with them, the regularities of changes in the reduced viscosity of the obtained modified polydimethylsiloxanes were analyzed. It has been established that the reduced viscosity of polydimethylsiloxanes increases with an increase of the modifier amphiphilicity. This is due to the occurrence of intermolecular interactions because the specific interaction of amphiphilic silica derivatives with polydimethylsiloxane macromolecules. When using amphiphilic derivatives of silica as a modifier of the resulting polydimethylsiloxane to a content of 6 wt% hydrophobic fragment in their composition, modification of polydimethylsiloxanes does not affect their rheological characteristics. This is due to the presence of polyoxyethylene branches in the composition of the modifier, which creates a cavity for the trapping of K+ ions, as in the crown ether, they perform only a catalytic function, which leads to an increase in the rate of the process. However, starting from 10 % wt the content of the hydrophobic component in the composition of the modifier, the reduced viscosity of the obtained polydimethylsiloxane increases due to the occurrence of intermolecular interactions between the modifier and the obtained polydimethylsiloxane. It was noted that polydimethylsiloxane obtained using only polyoxyethylene glycol as a modifier exhibits viscosity characteristics lower than polydimethylsiloxane obtained by the anionic mechanism without using any modifiers.

SYNTHESIS AND PROPERTIES OF NEOGLYCOLIPIDS BASED ON 2-AMINO-2-HYDROXYMETHYLPROPANE-1,3-DIOL

The use of TRIS derivatives as the kernels of branching fragments is a modern method of preparing carbohydrate-containing dendrimer-like amphiphiles. A scheme of the synthesis of derivatives of trivalent neoglycolipids with terminal residues of D-mannose and a branching component based on 2-amino-2-hydroxymethylpropene-1,3-diol (TRIS) differing in the degree of saturation of the hydrocarbon chains is developed. The preparation of the hydrophilic part of the target molecules was carried out with the use of the reaction of 1,3-dipolar cycloaddition followed by conjugation with the hydrophobic component according to the carbodiimide method with the addition of HOBt as a catalyst. Approaches to the formation of target designs - liposomes based on phosphatidylcholine and synthesized neoglycolipids - and their physical and chemical properties, such as the size of particles and stability are investigated. The activity of the obtained compounds in the composition of liposomes loaded with the antibiotic meropenem with respect to Escherichia coli strain is carried out. An opportunity of changing the profile of the action of a liposome sample containing neoglycolipids by choosing various methods of its preparation that is promising for further research in this direction is revealed.

The impact of the structuring of hydrotropes in water on the mesoscale solubilisation of a third hydrophobic component

The complex structuring of alcohols in water influences the mesoscale solubilisation of a third component depending on its nature.

Preparation and Characterization of Bionanocomposite Films Made from Carrageenan, Beeswax and ZnO Nanoparticles

The objective of this study was to develop biopolymer based films as alternative of synthetic petroleum based-packaging. The ZnO NPs (0.5 and 1% w/w carrageenan) and beeswax (3% v/v), as hydrophobic component, were incorporated into carrageenan polymer to produced bionanocomposite films. The resulting films were characterized using SEM. The physical and mechanical properties of films were also investigated. The addition of ZnO NPs and beeswax resulted in different morphological surface as well as influenced the surface color of carrageenan film. Incorporation of ZnO NPs increased TS and EAB of the film, while WVTR decreased. Furthermore, the presence of beeswax within the carrageenan and or its nanocomposite films promoted synergistic effect with ZnO NPs in reducing WVTR and EAB, however decreased TS of films. Therefore, these bionanocomposite films were potentially used in packaging industry to maintain the quality of food stuffs.

Microneedle-array patches loaded with hypoxia-sensitive vesicles provide fast glucose-responsive insulin delivery

A glucose-responsive “closed-loop” insulin delivery system mimicking the function of pancreatic cells has tremendous potential to improve quality of life and health in diabetics. Here, we report a novel glucose-responsive insulin delivery device using a painless microneedle-array patch (“smart insulin patch”) containing glucose-responsive vesicles (GRVs; with an average diameter of 118 nm), which are loaded with insulin and glucose oxidase (GOx) enzyme. The GRVs are self-assembled from hypoxia-sensitive hyaluronic acid (HS-HA) conjugated with 2-nitroimidazole (NI), a hydrophobic component that can be converted to hydrophilic 2-aminoimidazoles through bioreduction under hypoxic conditions. The local hypoxic microenvironment caused by the enzymatic oxidation of glucose in the hyperglycemic state promotes the reduction of HS-HA, which rapidly triggers the dissociation of vesicles and subsequent release of insulin. The smart insulin patch effectively regulated the blood glucose in a mouse model of chemically induced type 1 diabetes. The described work is the first demonstration, to our knowledge, of a synthetic glucose-responsive device using a hypoxia trigger for regulation of insulin release. The faster responsiveness of this approach holds promise in avoiding hyperglycemia and hypoglycemia if translated for human therapy.