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Silver nanoparticles (AgNPs) are well known for their unique physical and chemical properties, which can be incorporated into a wide range of applications. The growing resistance of microorganisms to antimicrobial compounds promoted the use of AgNPs in antimicrobial therapy. AgNPs can be obtained using physical and chemical methods, but these technologies are highly unfriendly to nature and produce large amounts of side compounds (for example, sodium borohydride and N,N-dimethylformamide). Therefore, alternative technologies are required for obtaining AgNPs. This report focuses on the biosynthesis of silver nanoparticles through the reduction of Ag+ with the cell-free secretomes of four Geobacillus bacterial strains, namely, 18, 25, 95, and 612. Only a few studies that involved Geobacillus bacteria in the synthesis of metal nanoparticles, including AgNPs, have been reported to date. The silver nanoparticles synthesized through bio-based methods were characterized using UV–Vis spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), and zeta potential measurements. UV–Vis spectroscopy showed a characteristic absorbance peak at 410–425 nm, indicative of AgNPs. SEM analysis confirmed that most nanoparticles were spherical. DLS analysis showed that the sizes of the obtained AgNPs were widely distributed, with the majority less than 100 nm in diameter, while the zeta potential values ranged from −25.7 to −31.3 mV and depended on the Geobacillus spp. strain.

β-glucans are known as biological response modifiers. However, different sources can result in structural differences and as a result differences in their biological activity. The hot water extraction method allows to obtain, high molecular weight β-glucans without altering their structure by using strong chemicals, such as alkalis or acids. Analysis of β-glucans by FT-IR and NMR spectroscopy in solid state is superior to analysis in solution as it allows researchers to study the preserved structure of the extracted polysaccharides. FT-IR spectroscopy was used in this study to make side-by-side comparison analysis of hot water extracted β-glucans from different yeast sources. NMR spectroscopy was used to confirm findings made by FT-IR spectroscopy. Extracted β-glucans exhibit characteristic structure of β-1,3/1,6-linked glucans with noticeable levels of proteins, possibly in a form of oligopeptides, chitin and other impurities. β-glucans obtained from C. guilliermondii, P. pastoris and S. pastorianus exhibited higher protein content. Differences in mannan, chitin and α-glucan content were also observed; however, the species-specific structure of obtained β-glucans could not be confirmed without additional studies. Structural analysis of high molecular weight β-glucans in solid state by FT-IR spectroscopy is difficult or limited due to band intensity changes and overlapping originating from different molecules.

Summary: Information regarding the protective anti‐SARS‐CoV‐2 antibody levels and the effectiveness of the mRNA vaccines against the Omicron variant in patients with haematological malignancies is limited. We prospectively followed two times BNT162b2 vaccinated oncohaematological patients (n = 1010) without prior COVID‐19 for PCR‐confirmed breakthrough infections during the Alpha/Delta and the Omicron phases of the pandemic. Anti‐S1‐IgG levels were longitudinally monitored in patients who had received the third (booster) vaccine dose. Patients with anti‐S1‐IgG levels <50 BAU/mL 1 month after the booster had a higher risk of Omicron infections (RR 1.91; 95% CI 1.39–2.63; p = 0.0001) and severe infections (RR 8.74; 95% CI 3.99–19.1; p < 0.0001). Conversely, the risk of severe COVID‐19 was <1% with anti‐S1‐IgG levels >500 BAU/mL and neutralizing antibody concentrations >50 U/mL. The risks of breakthrough Omicron infections (HR 0.55; 95% CI 0.32–0.96; p = 0.034) and severe COVID‐19 (HR 0.27; 95% 0.11–0.7; p = 0.0074) were lower among patients who had received the booster dose. In conclusion, low antibody levels are associated with significantly increased risk of both the breakthrough Omicron infections and severe COVID‐19. The third mRNA vaccine dose improved the protection against the Omicron and reduced the risk of severe disease. [ABSTRACT FROM AUTHOR]