ABSTRACT
The spherical materials TiO2-SiO2-P2O5/CaO, TiO2-SiO2-P2O5/La2O3, and TiO2-SiO2-P2O5/ZnO deposited on the Tokem-250 cation exchanger have been synthesized with an alcoholic solution by the sol-gel method. The macroporous cation exchanger Tokem-250, which has high Ca2+, Zn2+, and La3+ ion selectivity, was used in the present study. This material has the ability to precipitate and mineralize calcium phosphates on its surface in biological media, since it has high porosity, a homogeneous structure with a uniform variation of elements, and the presence of active centers (Si4+, Ti4+) on the surface. The effect of lanthanum and zinc additives on biological properties has been studied. It was established that accumulation of Ca2+ and Mg2+ occurs faster on the surface of TiO2-SiO2-P2O5/ZnO in the SBF (simulated body fluid) model solution, showing higher reaction capacity. The amount of calcium and phosphorus ions on the surface of sample TiO2-SiO2-P2O5/La2O3 is greater due to the ability of lanthanum to coordinate a large number of ions (lanthanum coordination number is 10). The presence of zinc ions in the system causes the partial hemoglobin release from erythrocytes into the supernatant fluid. The samples with lanthanum ions reduce the amount of protein in plasma after incubation, which has a positive effect on the practical application.
ABSTRACT
The TiO2-SiO2-Ag/fiberglass with antibacterial properties under UV light irradiation was synthesized. The effects of compositions of TiO2-SiO2-Ag/fiberglass, optical, and textural characteristics on the antibacterial activity were studied. The TiO2-SiO2-Ag film was coated on the surface of fiberglass carrier filaments. The temperature effect on the formation of the TiO2-SiO2-Ag film was established by thermal analysis, and the temperature treatment mode was selected as 300 °C for 30 min, 400 °C for 30 min, 500 °C for 30 min, and 600 °C for 30 min. The influence of silicon oxide and silver additives on the antibacterial properties of TiO2-SiO2-Ag films was established. Increasing the treatment temperature of the materials up to 600 °C increased the thermal stability of the titanium dioxide anatase phase, while the values of optical characteristics decreased: the film thickness decreased to 23.92 ± 1.24 nm, the refractive index decreased to 2.154 ± 0.002, the energy of the band gap width decreased to 2.8 ± 0.5, and the light absorption shifted to the visible-light regime, which is important for photocatalytic reactions. The results showed that the use of TiO2-SiO2-Ag/fiberglass allows significant decrease in the value of CFU microbial cells to 125 CFU m-3.
ABSTRACT
A facile synthesis method was developed to synthesize TiO2-SiO2-P2O5/CaO or TiO2-SiO2-P2O5/ZnO with a core-shell structure. The carboxylic cation exchanger Tokem-250 has a high selectivity for Ca2+/Zn2+ ions and was used in this study. The framework of the material in the shell was TiO2-SiO2-P2O5, and the inner part was filled with CaO (sample TiO2-SiO2/CaO) or ZnO (sample TiO2-SiO2-P2O5/ZnO). A stepwise heat treatment (drying in a drying oven at 60 °C for 30 min, then annealing in a muffle furnace for 30 min at 150, 250, and 350 °C, at 600 °C for 6 h, and at 800 °C for 1 h) was needed to obtain a homogeneous material. The poly(vinyl alcohol) was used as a binding additive. The obtained composites were characterized by a regular structure and highly developed surface. The samples exhibit bioactive properties in the simulated body fluid (SBF) solution, since the surface contains active centers (Si4+, Ti4+) which contribute to mineralization and precipitation of the calcium-phosphate compounds on the surface from biological media. The TiO2-SiO2-P2O5/CaO-PVA samples did not exceed acceptable hemolysis levels for medical materials.
ABSTRACT
Photoactive, optically transparent heterostructures from silver nanowires and titanium dioxide were obtained by the sol-gel method on the surface of a polyethylene terephthalate film. The characteristics of optical transmission on the wavelength and those of dielectric permittivity, conductivity and dissipation on frequency in the range of 25-1,000,000 Hz were investigated.
ABSTRACT
Spherical biomaterials based on Tokem-200 cationic exchange resin were synthesized from solutions by the sol-gel method. The material framework is represented by TiO2-SiO2, and the inner part is filled with CaO (sample TiO2-SiO2/CaO). A stepwise heat treatment (drying at 60 °C) annealing at 150, 250, and 350 °C, each for 30 min, at 600 °C for 6 h, and 800 °C for 1 h is required to obtain a homogeneous material. In simulated body fluid solution, the sample exhibited bioactive properties, and gelatin could be used as a binding additive.
ABSTRACT
The calcium phosphate spherical material with a hierarchical structure has been used as a bone implantation material. To improve the properties of the implant material, the compositions of calcium phosphate, silicon, and titanium are crucial. The presence of silicon on the surface of the phosphate-calcium material accelerates the bonding of the implant with the bone (osseointegration). The aim of this work was to develop a sol-gel method to prepare spherical calcium-phosphate@TiO2-SiO2 biomaterials for bone implantation. The CaO@TiO2-SiO2 biomaterial with a core-shell structure was synthesized by the sol-gel method. The biological properties of the materials were studied with a simulated body fluid (SBF). The sample had a spherical shape. The sample exhibited bioactive properties because an increase in the content of calcium and phosphorus ions in the shell and the presence of precipitated ions from the solution were detected on the surface. The TiO2-SiO2 framework was uniformly fixed on the CaO core. Heat treatment of the hybrid mesostructure led to the formation of mesoporous materials with a specific regular structure in the nanometer size in the shell, which is necessary for the fixation of biological cells when the sample is introduced into the biological medium. The formation of a calcium-phosphate layer on the materials and the release of soluble silicon and calcium ions into the SBF are the key factors for the rapid connection of these materials with tissue. The results demonstrate that the CaO@TiO2-SiO2 biomaterial with a core-shell structure is a good candidate for bone implantation.
ABSTRACT
A calcium-phosphate system was obtained by sol-gel method from 0.4 M solutions based on ethyl alcohol, tetraethoxysilane, phosphoric acid, calcium nitrate, and magnesium nitrate, sodium chloride. Compositions with different contents of CaO, Na2O, and MgO were prepared. After maturation of the solutions, heat treatments were applied at 60 °C for 30 min; and followed by 600 °C and 800 °C for 1 h. Solution with 20 wt% MgO was found suitable for film production. The physicochemical processes of the formation of materials were studied, including the main stages: removal of physically bound and chemically bound water, combustion of alcohol and the products of thermo-oxidative destruction of ethoxy groups, and crystallization processes. The phase composition and structure of the films obtained were established at 600 °C and above when crystalline forms of SiO2, CaSiO3, Ca2P2O7, and complex phosphates were fixed. In the system with the addition of magnesium ions, ß-cristobalite SiO2 and stenfieldt Mg3Ca3(PO4)4 were detected; however, a crystalline sample could only be obtained at 800 °C. In the system with sodium ions, chemical compounds Ca5(PO4)3Cl, NaCl, and SiO2 were determined. A uniform film coating was formed on the surface of the substrate. The introduction of sodium oxide into the SiO2-P2O5-CaO system increased the bioactivity of the materials obtained.