Purpose: Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO₂ P25), are among the most produced nanomaterials worldwide. The broad use of TiO₂ P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO₂ P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO₂ P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO₂ P25 for biological testing in A549 cells and to evaluate their biological effects. Methods: We determined the size and crystallinity of TiO₂ P25. We used four techniques for TiO₂ P25 dispersion. We estimated the colloid stability of TiO₂ P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO₂ P25 (0– 100 μg.mL^{− 1}) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy. Results: We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO₂ P25. Under these conditions, TiO₂ P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO₂ P25 in A549 cells were met, similar results on the biological effects of TiO₂ P25 were obtained in two independent cell laboratories. Conclusion: We optimized the experimental conditions of TiO₂ P25 preparation for toxicity testing in A549 cells. The results presented here on TiO₂ P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO₂ P25 as a reference material.

Mixed zirconium 4-sulfophenylphosphonate phenylphosphonates with formulae Zr(HO₃SC₆H₄PO₃)_1.8(C₆H₅PO₃)_0.2·2.6H₂O, Zr(HO₃SC₆H₄PO₃)_1.3(C₆H₅PO₃)_0.7·2H₂O, and Zr(HO₃SC₆H₄PO₃)_0.7(C₆H₅PO₃)_1.3·3.6H₂O (generally, ZrSPhP) were intercalated with a series of amino alcohols, H₂N(CH₂)_nOH, where n = 2 to 6, and triethylamine. It was found that in the case of amino alcohols the basal spacing of the intercalates increases linearly with n. The intercalates prepared can be exfoliated either by sonication or by the action of high-shear forces. The use of a high-shear force disperser is a more efficient exfoliation method, as it provides lamellas with larger lateral dimensions in a much shorter time. It was found that amino alcohols provide roughly the same results regardless of the length of their carbon chain. As follows from atomic force microscopy measurements, triethylamine is the most appropriate exfoliation agent for ZrSPhP as it produces platelets with the largest lateral size and the lowest amount of defects.

This article studies the photocatalytic activity of three types of industrially produced TiO₂ powder (P25, CG100 and CG300) incorporated into a parent geopolymer matrix, and their pure counterparts, based on the decomposition of Rhodamine B dye. Rhodamine B dye is applied as a model substance because it is frequently used in the textile industry and thus may be present in the wastewater. The average particle size, specific surface area and mineralogical composition of TiO₂ powders have been determined. The geopolymer matrix works well as a supporting material for the CG100 and P25 pure types of TiO₂ powder as these input materials have better properties such as a higher average particle size, lower specific surface area, mineralogicalcomposition, etc., than the CG300 TiO₂ powder. These properties (or their combination) affect the photocatalytic activity of the resulting materials, which may thus become advanced composites with an additional purifying ability, e.g., materials that can be used for wastewater treatment or air purification.

Layered nanoparticles with surface charge are explored as rheological modifiers for extrudable materials, utilizing their ability to induce electrostatic repulsion and create a house-of-cards structure. These nanoparticles provide mechanical support to the polymer matrix, resulting in increased viscosity and storage modulus. Moreover, their advantageous aspect ratio allows for shear-induced orientation and decreased viscosity during flow. In this work, we present a synthesis and liquid-based exfoliation procedure of phenylphosphonate-phosphate particles with enhanced ability to be intercalated by hydrophilic polymers. These layered nanoparticles are then tested as rheological modifiers of sodium alginate. The effective rheological modification is proved as the viscosity increases from 10¹ up to 10³ Pa·s in steady state. Also, shear-thinning behavior is observed. The resulting nanocomposite hydrogels show potential as an extrudable bioink for 3D printing in tissue engineering and other biomedical applications, with good shape fidelity, nontoxicity, and satisfactory cell viability confirmed through encapsulation and printing of mouse fibroblasts.