There is a growing interest in the utilization of metal oxide nanoparticles as antimicrobial agents. This review will focus on titanium dioxide nanoparticles (TiO₂ NPs), which have been demonstrated to exhibit high antimicrobial activity against bacteria and fungi, chemical stability, low toxicity to eukaryotic cells, and therefore high biocompatibility. Despite the extensive research conducted in this field, there is currently no consensus on how to enhance the antimicrobial efficacy of TiO₂ NPs. The aim of this review is to evaluate the influence of various factors, including particle size, shape, composition, and synthesis parameters, as well as microbial type, on the antibacterial activity of TiO₂ NPs against bacteria and fungi. Furthermore, the review offers a comprehensive overview of the methodologies employed in the synthesis and characterization of TiO₂ NPs. The antimicrobial activity of TiO₂ exhibits a weak dependence on the microorganism species. A tendency towards increased antibacterial activity is observed with decreasing TiO₂ NP size. The dependence on the shape and composition is more pronounced. The most pronounced antimicrobial potential is exhibited by amorphous NPs and NPs doped with inorganic compounds. This review may be of interest to specialists in biology, medicine, chemistry, and other related fields.

In recent decades, studies on the functional features of Se nanoparticles (SeNP) have gained great popularity due to their high biocompatibility, stability, and pronounced selectivity. A large number of works prove the anticarcinogenic effect of SeNP. In this work, the molecular mechanisms regulating the cytotoxic effects of SeNP, obtained by laser ablation, were studied by the example of four human cancer cell lines: A-172 (glioblastoma), Caco-2, (colorectal adenocarcinoma), DU-145 (prostate carcinoma), MCF-7 (breast adenocarcinoma). It was found that SeNP had different concentration-dependent effects on cancer cells of the four studied human lines. SeNP at concentrations of less than 1 μg/mL had no cytotoxic effect on the studied cancer cells, with the exception of the A-172 cell line, for which 0.5 μg/mL SeNP was the minimum concentration affecting its metabolic activity. It was shown that SeNP concentration-dependently caused cancer cell apoptosis, but not necrosis. In addition, it was found that SeNP enhanced the expression of pro-apoptotic genes in almost all cancer cell lines, with the exception of Caco-2 and activated various pathways of adaptive and pro-apoptotic signaling pathways of UPR. Different effects of SeNP on the expression of ER-resident selenoproteins and selenium-containing glutathione peroxidases and thioredoxin reductases, depending on the cell line, were established. In addition, SeNP triggered Ca²⁺ signals in all investigated cancer cell lines. Different sensitivity of cancer cell lines to SeNP can determine the induction of the process of apoptosis in them through regulation of the Ca²⁺ signaling system, mechanisms of ER stress, and activation of various expression patterns of genes encoding pro-apoptotic proteins.

Long-lived luminescence in the blue region was found to occur in deionized water saturated with atmospheric gases following mechanical shaking. Luminescence intensity decreased exponentially after the cessation of stress. During vigorous mechanical shaking, we observed gas bubbles in solution, and the liquid–gas interface area increased noticeably. At the same time, the concentration of molecular oxygen decreased, which could not be attributed to the water warming up with exposure to mechanical stress. However, deaerated water rapidly became saturated with gases following mechanical stress. The recommendation that cell culture media should be mixed after they are removed from the fridge in order to allow saturation with oxygen is probably misleading. It was shown that gases existed in water both in the form of individual molecules and nanobubbles. Mechanical stress did not influence the number or size of nanobubbles. While gas nanobubbles were absent in freshly prepared deaerated water, they appeared following exposure to mechanical stress. In addition, in mechanically treated gas-saturated water, there was seemingly an equilibrium shift towards the decomposition of carbonic acid to water and carbon dioxide. At the same time, the pH of water tended to increase immediately after mechanical stress. It was demonstrated that reactive oxygen species (ROS) form in gas-saturated water under mechanical stress (30 Hz, amplitude of 5 mm). The relative generation rate of hydrogen peroxide and of the hydroxyl radical was 1 nM/min and 0.5 nM/min, respectively. It was found that with an increase in the frequency of mechanical action (f), the rate of ROS generation increased in proportion to f ². The major pathways for hydrogen peroxide generation are probably associated with the formation of singlet oxygen and its further reduction, and the alternative pathway is the formation of hydrogen peroxide as a result of hydroxyl radical recombination.

A low-temperature technology was developed for producing a nanocomposite based on poly (lactic-co-glycolic acid) and zinc oxide nanoparticles (ZnO-NPs), synthesized by laser ablation. Nanocomposites were created containing 0.001, 0.01, and 0.1% of zinc oxide nanoparticles with rod-like morphology and a size of 40–70 nm. The surface of the films from the obtained nanomaterial was uniform, without significant defects. Clustering of ZnO-NPs in the PLGA matrix was noted, which increased with an increase in the concentration of the dopant in the polymer. The resulting nanomaterial was capable of generating reactive oxygen species (ROS), such as hydrogen peroxide and hydroxyl radicals. The rate of ROS generation increased with an increase in the concentration of the dopant. It was shown that the synthesized nanocomposite promotes the formation of long-lived reactive protein species, and is also the reason for the appearance of a key biomarker of oxidative stress, 8-oxoguanine, in DNA. The intensity of the process increased with an increase in the concentration of nanoparticles in the matrix. It was found that the nanocomposite exhibits significant bacteriostatic properties, the severity of which depends on the concentration of nanoparticles. In particular, on the surface of the PLGA–ZnO-NPs composite film containing 0.001% nanoparticles, the number of bacterial cells was 50% lower than that of pure PLGA. The surface of the composite is non-toxic to eukaryotic cells and does not interfere with their adhesion, growth, and division. Due to its low cytotoxicity and bacteriostatic properties, this nanocomposite can be used as coatings for packaging in the food industry, additives for textiles, and also as a material for biomedicine.

Despite the use of sorafenib as one of the most effective drugs for the treatment of liver cancer, its significant limitations remain—poor solubility, the need to use high doses with the ensuing complications on healthy tissues and organs, and the formation of cell resistance to the drug. At the same time, there is more and more convincing evidence of the anticancer effect of selenium-containing compounds and nanoparticles. The aim of this work was to develop a selenium–sorafenib nanocomplex and study the molecular mechanisms of its anticancer effect on human hepatocyte carcinoma cells, where nanoselenium is not only a sorafenib transporter, but also an active compound. We have created a selenium–sorafenib nanocomplex based on selenium nanoparticles with size 100 nm. Using vitality tests, fluorescence microscopy, and PCR analysis, it was possible to show that selenium nanoparticles, both by themselves and doped with sorafenib, have a pronounced pro-apoptotic effect on HepG2 cells with an efficiency many times greater than that of sorafenib (So). “Naked” selenium nanoparticles (SeNPs) and the selenium–sorafenib nanocomplex (SeSo), already after 24 h of exposure, lead to the induction of the early stages of apoptosis with the transition to the later stages with an increase in the incubation time up to 48 h. At the same time, sorafenib, at the studied concentrations, began to exert a proapoptotic effect only after 48 h. Under the action of SeNPs and SeSo, both classical pathways of apoptosis induction and ER-stress-dependent pathways involving Ca²⁺ ions are activated. Thus, sorafenib did not cause the generation of Ca²⁺ signals by HepG2 cells, while SeNPs and SeSo led to the activation of the Ca²⁺ signaling system of cells. At the same time, the selenium–sorafenib nanocomplex turned out to be more effective in activating the Ca²⁺ signaling system of cells, inducing apoptosis and ER stress by an average of 20–25% compared to “naked” selenium nanoparticles. Our data on the mechanisms of action and the created nanocomplex are promising as a platform for the creation of highly selective and effective drugs with targeted delivery to tumors.

The potential of the method of fluorescence spectroscopy for the detection of damage and diseases of fruits and vegetables was studied. For this purpose, the spectra of fluorescence of healthy and rotten apples and potatoes have been investigated. Excitation of samples was carried out using a continuous semiconductor laser with a wavelength of 405 nm and a pulsed solid-state laser with a wavelength of 527 nm. Peaks in the region of 600–700 nm in rotten samples were shifted towards shorter wavelengths for most samples in both modes of spectroscopy. The differences in the fluorescence spectra of a healthy and rotten apple surface have been revealed to be in the spectral range of 550–650 nm for 405 nm continuous excitation. When exposed to a laser in a pulsed mode (527 nm), the contribution of the 630 nm peak in the spectrum increases in rotten samples. The observed differences make it possible to use this method for separating samples of healthy and rotten fruits and vegetables. The article paid attention to the influence of many factors such as sample thickness, time after excitation, contamination by soil and dust, cultivar, and location of the probing on fluorescence spectra.