Toxicity assessment of core-shell and superabsorbent polymers in cell-based systems

The identification of health risks arising from occupational exposure to submicron/nanoscale materials is of particular interest and toxicological investigations designed to assess their hazardous properties can provide valuable insights. The core-shell polymers poly (methyl methacrylate)@poly (methacrylic acid-co-ethylene glycol dimethacrylate) [PMMA@P (MAA-co-EGDMA)] and poly (n-butyl methacrylate-co-ethylene glycol dimethacrylate)@poly (methyl methacrylate) [P (nBMA-co-EGDMA)@PMMA] could be utilized for the debonding of coatings and for the encapsulation and targeted delivery of various compounds. The hybrid superabsorbent core-shell polymers poly (methacrylic acid-co-ethylene glycol dimethacrylate)@silicon dioxide [P (MAA-co-EGDMA)@SiO₂] could be utilized as internal curing agents in cementitious materials. Therefore, the characterization of their toxicological profile is essential to ensure their safety throughout manufacturing and the life cycle of the final products. Based on the above, the purpose of the present study was to assess the acute toxic effects of the above mentioned polymers on cell viability and on cellular redox state in EA. hy926 human endothelial cells and in RAW264.7 mouse macrophages. According to our results, the examined polymers did not cause any acute toxic effects on cell viability after any administration. However, the thorough evaluation of a panel of redox biomarkers revealed that they affected cellular redox state in a cell-specific manner. As regards EA. hy926 cells, the polymers disrupted redox homeostasis and promoted protein carbonylation. Concerning RAW264.7 cells, P (nBMA-co-EGDMA)@PMMA caused disturbances in redox equilibrium and special emphasis was placed on the triphasic dose-response effect detected in lipid peroxidation. Finally, P (MAA-co-EGDMA)@SiO₂ activated cellular adaptive mechanisms in order to prevent from oxidative damage.

Strontium hexaferrite nanomagnets suspended in a cosmetic preparation: a convenient tool to evaluate the biological effects of surface magnetism on human skin

BACKGROUND/PURPOSE

Magnetic therapy has been popular for ages, but its therapeutic abilities remain to be demonstrated. We aimed to develop a homogeneous, stable dispersion of magnetic nanoparticles in a skin-care preparation, as a tool to analyze the biological and physiological effects of superficial magnetism in skin.

METHODS

SrFe(12)O(19) nanoparticles were generated by ultrasound, dispersed in glycerol, stabilized in Dermud cream and permanently magnetized. The magnetic cream was applied on the epidermis of human skin organ cultures. The effects on UV-induced cell toxicity, apoptosis and inflammatory cytokine expression were analyzed. A clinical test was performed to check skin moisturization.

RESULTS

Nanomagnets were found to be homogenously and stably dispersed. After magnetization, the preparation generated a magnetic field of 1-2 G. Upon cream application, no cytotoxicity and no impairment of cellular vitality were found after 24 and 48 h, respectively. The anti-apoptotic and anti-inflammatory properties of Dermud were not modified, but its long-term effect on moisturization in vivo was slightly increased.

CONCLUSION

Nanomagnetic Dermud cream can be used as a tool to analyze the biological effects of nanomagnets dispersed on the skin surface at the cellular and molecular levels, thus allowing to explore the possible therapeutic uses of superficial magnetism for skin care.

Ultrasound radiation as a "throwing stones" technique for the production of antibacterial nanocomposite textiles

Ultrasound irradiation was applied as a "throwing stones" technique for coating cotton bandages with MgO and Al(2)O(3) commercially obtained nanoparticles. The homogeneous distribution of the nanoparticles without any aggregation on the fabrics was demonstrated. The antibacterial activities of the MgO/Al(2)O(3)-fabric nanocomposite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a concentration <1% (by weight), was detected.

Antibacterial properties of an in situ generated and simultaneously deposited nanocrystalline ZnO on fabrics

Zinc oxide (ZnO) nanoparticles were synthesized and deposited on the surface of cotton fabrics using ultrasound irradiation. Optimization of the process resulted in a homogeneous distribution of ZnO nanocrystals, 30 nm in size, on the fabric surface. The mechanism of the ultrasound-assisted coating was proposed. The antibacterial activities of the ZnO-fabric composite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a 0.75% coated fabric (wt %), was demonstrated.

Selective oxidation of CO in the presence of air over gold-based catalysts Au/TiO2/C (sonochemistry) and Au/TiO2/C (microwave)

Two model catalysts, Au/TiO2/C (S) (sonochemically derived) and Au/TiO2/C (M) (microwave derived), were produced by employing ultrasound irradiation and microwave irradiation, respectively. The deposition of gold colloids onto the support powders, TiO2/C, was accomplished by using a solvated metal atom impregnation (SMAI) method. The SMAI technique provides highly-dispersed gold particles on the TiO2/C support. The catalytic performance of Au based catalysts 1 wt% Au-TiO2/C (S) and 1 wt%Au-TiO2(M)/C (M) have been tested for the oxidation of CO in the temperature range of 0-300 degrees C and compared to that of 1 wt% Au-TiO2 (Degussa-P25). A boost in the conversion of CO was observed for the sonochemically-derived catalyst, Au/TiO2/C (S), at low temperature. Hence, the reactivity order found for CO oxidation is (Au/TiO2/C (S)>Au/TiO2 (P25)>Au/TiO2/C (M)).

Preparation of porous cobalt and nickel oxides from corresponding alkoxides using a sonochemical technique and its application as a catalyst in the oxidation of hydrocarbons

Porous nickel and cobalt oxides were prepared using their alkoxides as inorganic precursors. The stabilization of the mesostructure is especially critical for divalent elements such as Ni and Co, which do not form any network structure, like silicates. The lack of a network-forming multivalent bond is the probable reason why no stable mesoporous oxides have been synthesized for divalent elements yet. Here we have reported our attempt to synthesize porous oxides of Ni and Co. Octadecylamine has been used as the organic structure-directing agent. The product obtained was put under solvent extraction and calcination at various temperatures to remove the surfactant, followed by characterization using XRD, TEM and BET measurements. The FT/IR and thermal analyses (TGA and DSC) were also carried out for supporting information, such as extent of removal of surfactant from the pores of the metal oxide. A relatively better surface area has been obtained for the Co oxide, but in Ni the surface area found is not as good. A possible reason for that has been discussed. The porous (solvent extracted) cobalt oxide has been used as a catalyst in the oxidation reaction of cyclohexane in mild conditions. The catalyst has shown relatively better conversion of cyclohexane into cyclohexanone and cyclohexanol than the nanostructured cobalt oxide catalyst of regular structure.

Sonochemistry as a tool for preparation of porous metal oxides

The porous metal oxides are an important class of materials, because the surface area/volume ratio of a material is increased by many fold, making them very useful in surface-related applications. The mesoporous materials were discovered in the 1990s, and since then they have been excellent candidates for materials science research. These mesoporous materials are prepared by hydrolyzing the inorganic precursor (usually metal alkoxide) in an acid, basic, or neutral medium in the presence of an organic structure-directing agent, the surfactant, in a conventional method. Recently, we have demonstrated that the sonochemical technique can be employed for the synthesis of mesoporous metal oxides. The sonochemical method reduced the time period required for such synthesis by many fold, and also produced more stable structures. We got excellent results with silica, titania, yittria-stabilized zirconia (YSZ), and Fe2O3. We also used an inorganic precursor other than an alkoxide for the preparation of mesoporous metal oxides. In this article, we present some of the recent results on this topic.

Using sonochemical methods for the preparation of mesoporous materials and for the deposition of catalysts into the mesopores

Ultrasound radiation can be used to synthesize a variety of mesporous materials. The reaction time is considerably shorter than the conventional methods. Ultrasonic waves can be further used for the insertion of amorphous nanosized catalysts into the mesopores. A detailed study demonstrates that the nanoparticles are deposited as a monolayer on the inner mesopores walls without blocking them. When the ultrasonically prepared catalyst/mesoporous-subtrate composite is used in catalysis a high conversion into product is obtained.