02139nas a2200217   4500008004100000022001400041245010000055210006900155300001100224490000800235520146500243653000801708653000701716100001901723700002201742700002501764700002101789700002001810700001901830856007201849       2025                        eng d  a0141-813000aMultiscale analysis of mechanical and structural properties of agarose–silk fibroin hydrogels0 aMultiscale analysis of mechanical and structural properties of a  a1481330 v3303 a<p>This study provides a comprehensive characterization of the agarose–silk fibroin hydrogels, using atomic force microscopy and scanning transmission electron microscopy to analyse their structure and assess the effect of composition on mechanical properties via nanoindentation and rheological analysis. These measurements enabled determination of mechanical properties, including the elastic and viscoelastic moduli at both the micro- and macroscale. The hydrogels exhibited a wide range of moduli depending on different degrees of network crosslinking, influenced by varying concentrations of agarose (1 or 2&nbsp;wt%) and the percentage of fibroin fibres (0–4.5&nbsp;wt%) as an interpenetrating component. The viscoelastic modulus (G') and the elastic modulus determined using a relaxation model (E), were 5–57&nbsp;kPa and 1.2–110&nbsp;kPa, respectively. The adhesion energy of these hydrogels was determined from nanoindentation curves and analysed using the JKR model, with values ranging from 0.031 to 0.066&nbsp;J&nbsp;m−2. These results provide insight into how the hydrogels' microstructure influences their mechanical and transport properties. Incorporating fibroin into these gels modifies biological and biochemical characteristics of the gels, suggesting that such composite hydrogels could be further explored for potential applications in controlled release systems, extracellular matrix models, or tissue engineering scaffolds.</p>10aAIF10aMF1 aPlichta, Tomas1 aMrazova, Katerina1 aRichterova, Veronika1 aKhyrova, Marketa1 aLukes, Jaroslav1 aSepitka, Josef  uhttps://www.sciencedirect.com/science/article/pii/S014181302508690802109nas a2200277   4500008004100000022001400041245013300055210006900188300001200257490000800269520124000277653000701517653000701524100002101531700002301552700001901575700001901594700001501613700001901628700002501647700002201672700002201694700002101716700002201737856007201759       2022                        eng d  a0141-813000aThe role of polyhydroxyalkanoates in adaptation of Cupriavidus necator to osmotic pressure and high concentration of copper ions0 arole of polyhydroxyalkanoates in adaptation of Cupriavidus necat  a977-9890 v2063 a<p>Polyhydroxyalkanoates (PHA) are abundant microbial polyesters accumulated in the form of intracellular granules by numerous prokaryotes primarily as storage of carbon and energy. Apart from their storage function, the presence of PHA also enhances the robustness of the microbial cells against various stressors. In this work, we investigated the role of PHA in Cupriavidus necator, a model organism concerning PHA metabolism, for adaptation to osmotic pressure and copper ions. In long-term laboratory evolution experiments, the bacterial culture was cultivated in presence of elevated doses of sodium chloride or copper ions (incubations lasted 78 passages for Cu2+ and 68 passages for NaCl) and the evolved strains were compared with the wild-type strain in terms of growth and PHA production capacity, cell morphology (investigated by various electron microscopy techniques), activities of selected enzymes involved in PHA metabolism and other crucial metabolic pathways, the chemical composition of bacterial biomass (determined by infrared and Raman spectroscopy) and also considering robustness against various stressors. The results confirmed the important role of PHA metabolism for adaptation to both tested stressors.</p>10aBF10aMF1 aNovackova, Ivana1 aHrabalova, Vendula1 aSlaninova, Eva1 aSedlacek, Petr1 aSamek, Ota1 aKoller, Martin1 aKrzyzanek, Vladislav1 aHrubanova, Kamila1 aMrazova, Katerina1 aNebesarova, Jana1 aObruca, Stanislav  uhttps://www.sciencedirect.com/science/article/pii/S0141813022005712