The aim of this work was to study effect of the type of silica nanoparticles on the properties of nanocomposites for application in the guided bone regeneration (GBR). Two types of nanometric silica particles with different size, morphology and specific surface area (SSA) i.e., high specific surface silica (hss-SiO₂) and low specific surface silica (lss-SiO₂), were used as nano-fillers for a resorbable polymer matrix: poly(L-lactide-co-D,L-lactide), called PLDLA. It was shown that higher surface specific area and morphology (including pore size distribution) recorded for hss-SiO₂ influences chemical activity of the nanoparticle; in addition, hydroxyl groups appeared on the surface. The nanoparticle with 10 times lower specific surface area (lss-SiO₂) characterized lower chemical action. In addition, a lack of hydroxyl groups on the surface obstructed apatite nucleation (reduced zeta potential in comparison to hss-SiO₂), where an apatite layer appeared already after 48 h of incubation in the simulated body fluid (SBF), and no significant changes in crystallinity of PLDLA/lss-SiO₂ nanocomposite material in comparison to neat PLDLA foil were observed. The presence and type of inorganic particles in the PLDLA matrix influenced various physicochemical properties such as the wettability, and the roughness parameter note for PLDLA/lss-SiO₂ increased. The results of biological investigation show that the bioactive nanocomposites with hss-SiO₂ may stimulate osteoblast and fibroblast cells’proliferation and secretion of collagen type I. Additionally, both nanocomposites with the nanometric silica inducted differentiation of mesenchymal cells into osteoblasts at a proliferation stage in in vitro conditions. A higher concentration of alkaline phosphatase (ALP) was observed on the material modified with hss-SiO₂ silica.

Groundwater treatment residuals (GWTRs) are safe waste materials generated during drinking water treatment. GWTRs are mainly deposited in landfills, but the preferred solution should be reused or utilized for some components. To ensure proper sludge management, it is important to provide quality, chemical composition, and texture characteristics of GWTRs. Therefore, in this study, we aimed to investigate and compare the features of GWTRs collected from four water treatment plants. GWTRs were characterized by X-ray diffraction (XRD); scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS); Fourier transform infrared spectroscopy (FTIR); thermogravimetric, differential thermogravimetric, and differential thermal analysis (TG, DTG, and DTA, respectively); X-ray fluorescence (XRF); inductively coupled plasma optical emission spectrometry (ICP-OEP); specific surface area (S_BET) measurement; and determination of the isoelectric point (pH_IEP). According to the results, GWTRs are poor crystalline materials that are predominantly composed of ferrihydrite with minor calcite and quartz admixture. They formed heterogeneously mixed particles with irregular shapes. They were mainly composed of iron oxides (32–55%), silica (4–28%), calcium oxide (4–17%), and manganese oxides (0.3–4.0%). They were found to be mesoporous with a large specific surface area. Due to their composition and texture characteristics, GWTRs demonstrate good adsorption properties toward different compounds such as heavy metals and metalloids.

Electrospinning was used to obtain multifunctional fibrous composite materials with a matrix of poly-ɛ-caprolactone (PCL) and 2 wt.% addition of a nanofiller: montmorillonite (MMT), montmorillonite intercalated with gentamicin sulphate (MMTG) or gentamicin sulphate (G). In the first stage, the aluminosilicate gallery was modified by introducing gentamicin sulfate into it, and the effectiveness of the intercalation process was confirmed on the basis of changes in the clay particle size from 0.5 µm (for MMT) to 0.8 µm (for MMTG), an increase in the interplanar distance d₀₀₁ from 12.3 Å (for MMT) to 13.9 Å (for MMTG) and altered clay grain morphology. In the second part of the experiment, the electrospinning process was carried out in which the polymer nonwovens with and without the modifier were prepared directly from dichloromethane (DCM) and N,N-dimethylformamide (DMF). The nanocomposite fibrous membranes containing montmorillonite were prepared from the same polymer solution but after homogenization with the modifier (13 wt.%). The degree of dispersion of the modifier was evaluated by average microarray analysis from observed area (EDS), which was also used to determine the intercalation of montmorillonite with gentamicin sulfate. An increase in the size of the fibers was found for the materials with the presence of the modifier, with the largest diameters measured for PCL_MMT (625 nm), and the smaller ones for PCL_MMTG (578 nm) and PCL_G (512 nm). The dispersion of MMT and MMTG in the PCL fibers was also confirmed by indirect studies such as change in mechanical properties of the nonwovens membrane, where the neat PCL nonwoven was used as a reference material. The addition of the modifier reduced the contact angle of PCL nonwovens (from 120° for PCL to 96° for PCL_G and 98° for PCL_MMTG). An approximately 10% increase in tensile strength of the nonwoven fabric with the addition of MMT compared to the neat PCL nonwoven fabric was also observed. The results of microbiological tests showed antibacterial activity of all obtained materials; however, the inhibition zones were the highest for the materials containing gentamicin sulphate, and the release time of the active substance was significantly extended for the materials with the addition of montmorillonite containing the antibiotic. The results clearly show that the electrospinning technique can be effectively used to obtain nanobiocomposite fibers with the addition of nonintercalated and intercalated montmorillonite with improved strength and increased stiffness compared to materials made only of the polymer fibers, provided that a high filler dispersion in the spinning solution is obtained.

Titanium boride (TiB₂) is a material classified as an ultra-high-temperature ceramic. The TiB₂ structure is dominated by covalent bonds, which gives the materials based on TiB₂ very good mechanical and thermal properties, making them difficult to sinter at the same time. Obtaining dense TiB₂ polycrystals requires a chemical or physical sintering activation. Carbon and molybdenum disilicide (MoSi₂) were chosen as sintering activation additives. Three series of samples were made, the first one with carbon additives: 0 to 4 wt.%; the second used 2.5, 5 and 10 wt.% MoSi₂; and the third with both additions of 2 wt.% carbon and 2.5, 5 and 10 wt.% MoSi₂. On the basis of the dilatometric sintering analysis, all additives were found to have a favourable effect on the sinterability of TiB₂, and it was determined that sintering TiB₂ with the addition of carbon can be carried at 2100 °C and with MoSi₂ and both additives at 1800 °C. The polycrystals were sintered using the hot-pressing technique. On the basis of the studies conducted in this work, it was found that the addition of 1 wt.% of carbon allows single-phase TiB₂ polycrystals of high density (>90%) to be obtained. The minimum MoSi₂ addition, required to obtain dense sinters with a cermet-like microstructure, was 5 wt.%. High density was also achieved by the materials containing both additives. The samples with higher MoSi₂ content, i.e., 5 and 10%, showed densities close to 100%. The mechanical properties, such as Young’s modulus, hardness and fracture toughness (K_Ic), of the polycrystals and composites were similar for samples with densities exceeding 95%. The Vickers hardness was 23 to 27 GPa, fracture toughness (K_IC) was 4 to 6 MPa·m^0.5 and the Young’s modulus was 480 to 540 GPa. The resulting TiB₂-based materials showed potential in high-temperature applications.