Upconverting nanoparticles (UCNPs) have attracted much attention in nanomedicine due to their ability to upconvert photons. However, their adverse effects hinder the biomedical applications. In this paper, bisphosphonate-modified poly(isobutylene-alt-maleicacid)-graft-poly(N,N-dimethylacrylamide)-coated NaYF4:Yb,Er,Pr UCNPs (UCNP@PIMAPDMA) nanoparticles were designed, which exhibited luminescence emission simultaneously in the visible and NIR-II regions. The developed UCNPs were characterized by a range of physicochemical methods, including transmission electron and energy dispersive microscopy (TEM and EDAX), dynamic light scattering (DLS), X-ray diffraction analysis (XRD), spectrofluorometry, X-ray photoelectron spectroscopy (XPS), and so forth. The UCNP@PIMAPDMA nanoparticles were also evaluated in cell cultures and experimental animals. The particles showed good biocompatibility with cultured human embryonic kidney HEK293 cells commonly used in toxicological studies. Neat UCNPs were cytotoxic towards these cells, which was confirmed by measuring their viability using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Blood serum proteins adhered to the surface of UCNP@PIMAPDMA particles, forming a protein corona that may contribute to particle biosafety. After intravenous injection of these particles into laboratory mice, there were no statistically significant changes in body mass of the treated animals. Also, no big adverse effects on blood cell profile, enzymatic and metabolic markers of hepatotoxicity and nephrotoxicity were observed. Finally, the application potential of UCNP@PIMAPDMA nanoparticles was confirmed by successfully imaging the cytoplasm of rat mesenchymal stem cells and rat C6 glioblastoma cells using laser scanning confocal microscopy.

Keywords: cytotoxicity | hematology parameters | polymer coating | protein corona | upconverting nanoparticles

UDC: 616.94:576.8.06:616.155.34:616.155.321]-002.828-092.9

   Background. Sepsis is a major global health problem, with fungal pathogens such as Candida albicans emerging as a significant cause of invasive infection. Fungal sepsis has a higher mortality rate than bacterial sepsis and is complicated by antifungal resistance. Although neutrophil extracellular traps (NETs) help to contain fungi, excessive NETs can contribute to inflammation and tissue injury. Understanding these mechanisms could reveal markers of disease activity and new therapeutic targets. Materials and Methods. Fungal sepsis was induced in twelve male BALB/c mice via an intraperitoneal injection of Meyerozyma guilliermondii (107 cells per mouse). Blood was collected at the beginning of the study and then on days 1–3, 7–9, and 13–15. Serum was analyzed for IgG, IgM, circulating immune complexes (ELISA), and extracellular DNA (fluorescence assay). 
   Results and Discussion. In mice with fungal sepsis, IgG levels remained stable while IgM levels increased significantly between days 7 and 9, before declining from day 13. IgG–IgM immune complexes peaked around days 8–9, reflecting active antigenantibody responses. Free DNA levels, which indicate NETs formation, increased by day 7 and then declined, showing early neutrophil activation followed by humoral control. Together, these findings suggest a coordinated immune response in which NETs and immune complexes contribute to both pathogen control and inflammation.
   Conclusion. Fungal sepsis induced by Meyerozyma guilliermondii resulted in early NETosis and an increase in IgM and immune complexes. IgM levels peaked on days 7–9 before declining. Unlike Candida albicans, this strain does not cause rapid lethality, enabling detailed tracking of disease progression over time. After day 9, immune parameters began to normalize, indicating the resolution of the acute phase and supporting the usefulness of this model for studying host immune dynamics in fungal sepsis.
   Keywords: fungal sepsis, Meyerozyma guilliermondii, acute inflammation, immune defense, circulating immune complexes, neutrophil extracellular traps
(NETs)

The effects of natural clinoptilolite originated from the Transcarpathian region in the Western Ukraine and its composites doped with metal ions were studied toward: (1) cultured pseudo-normal mammalian cell and murine macrophages; (2) neutrophils of blood of healthy human donors; (3) mice immunized with model antigen; (4) mice under air-pouch model for estimation of microvasculature damage; (5) Candida albicans fungi. Silver doping enhanced cytotoxic action of natural clinoptilolite, while zinc doping did not do that. Clinoptilolite-Ag(NH₃)²⁺ was non-toxic for murine macrophages and moderately toxic for human HEК293 cells. Toxicity of clinoptilolite-Ag⁺ composite toward HEК293 cells was comparable with the effect in positive control. Natural clinoptilolite and its silver derivatives enhanced the humoral immune response in mice and the levels of antibodies were comparable with such levels at response to standard adjuvant, which, however, damaged the microvasculature in mice. Furthermore, natural and Ag-enriched clinoptilolite were capable of activating neutrophils with a release of neutrophil extracellular traps. Finally, we showed that both clinoptilolite-Ag(NH₃)²⁺ and clinoptilolite-Ag+ possessed much higher antifungal activity toward Candida albicans compared to such activity of the nonmodified clinoptilolite, while their doping with zinc did not show such enhancement. Thus, the Transcarpathian clinoptilolite possesses low toxicity toward mammalian cells and activates neutrophils in vitro, while silver doping enhanced the cytotoxicity of this material. Silver-doped derivatives demonstrated stimulating action on antibody production and the antifungal effect. Thus, the developed clinoptilolite-based composites are perspective for use as novel natural immuno-stimulators and antifungal agents.

 Keywords Clinoptilolite · Cytotoxicity · Immune-stimulation · Antifungal activity

UDC 577.615.324-027.2.615.076

   Creation of novel remedies efficient in supporting wound healing remains an actual task in pharmacology. Hydrogels showed high efficiency in wound healing and tissue regeneration due to viscosity, elasticity and fluidity that provide them with functional characteristics similar to that in extracellular matrix. The aim of the study was to create chitosan-based hydrogels functionalized with different components (chondroitin-6-sulfate, hyaluronic acid, N-stearoylethanolamine) and to estimate their biocompatibility and biodegradability in vitro. For the first time, a lipid substance N-stearoylethanolamine (NSE) known as suppressor of pro-inflammatory cytokines expression was used as hydrogel component (1.95 mg/g). FTIR analysis confirmed the complexation of chitosan molecule with hyaluronate, chondroitin-6-sulfate, NSE. MTT-test and Trypan blue exclusion test were used to study hydrogels cytotoxicity towards human cells of different tissue origin. Biodegradability of hydrogels was evaluated using direct hydrogel contact with cells and cellindependent degradation. It was shown that chondroitin-6-sulfate (<2 mg/ml), hyaluronic acid (<2 mg/ml) and NSE (26 μg/ml) did not demonstrate significant toxic effects towards pseudonormal human cells of the MCF10A, HaCat, HEK293 lines and mouse cells of the Balb/3T3 line. The studied hydrogels were stable in saline solution, while in a complete culture medium containing 10% fetal bovine blood serum they underwent degradation in >24 h. The identified biodegradability of the chitosan-based hydrogels is important for the release of noncovalently immobilized NSE into biological medium. Further studies on laboratory animals with experimental wounds are expected to explore the potential of created hydrogels as anti-inflammatory
and wound-healing agents.
K e y w o r d s: chitosan hydrogels, chondroitin-6-sulfate, hyaluronic acid, N-stearoylethanolamine, FTIR analysis, human pseudonormal cells, toxicity, biodegradability

ILLUSTRATED STUDENT GUIDE is a study guide on histology, cytology and embryology for students of medical universities and academies of Ukraine. Its main purpose is to help students in self-preparing and in practical classes in studying microscopic slides of cells, tissues and organs, interpreting the obtained images and mastering specific histological and embryological terminology. The guideline was discussed and approved by Profile Methodological Commission for Medico-Biological Subjects. Protocol № 2, March 23, 2023.