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Item type:Publication, Access status: with files , Electron beam crosslinking as a strategy for the synthesis of pectin/PVA aerogels: effect of concentration and radiation dose(Multidisciplinary Digital Publishing Institute (MDPI), 2026-09-10); ; ; ; Radiation techniques represent an innovative and alternative method for polymer gelation or crosslinking; their application in aerogel research has not been extensively investigated. The irradiation of polymer solutions, either with or without a crosslinking agent, may result in stable polymer gels with a highly developed mesoporous structure. In this study, the effect of the pectin polysaccharide concentration, the presence of PVA, and the dose of ionizing radiation (27-58 kGy) were systematically investigated, particularly with respect to the structural, textural, and mechanical properties. The pectin/PVA and PVA were crosslinked in aqueous solution via ionizing radiation using an electron beam. The results demonstrated that the radiation crosslinking of a hydrophilic synthetic polymer in the presence of natural polysaccharides, such as pectin, is an effective strategy for engineering porous materials with a controlled structure, namely aerogels, of good stability, and favorable functional properties. The resulting composite aerogels were characterized by a BET-determined specific surface area of 200-241 m²/g and an estimated porosity of over 91%, compared with values of 28-46 m²/g, 0.22 g/cm³ and approximately 81.5% for aerogels produced using the freeze-method.Publicationtype: Journal Article34 22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Three-Dimensional-Bioprinted Non-Small Cell Lung Cancer Models in a Mouse Phantom for Radiotherapy Research(Multidisciplinary Digital Publishing Institute (MDPI), 2024-09-24); 40 38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Hierarchical coarse-grained strategy for macromolecular self-assembly : application to hepatitis B virus-like particles(Multidisciplinary Digital Publishing Institute (MDPI), 2022-11-24); ; ; ; Macromolecular self-assembly is at the basis of many phenomena in material and life sciences that find diverse applications in technology. One example is the formation of virus-like particles (VLPs) that act as stable empty capsids used for drug delivery or vaccine fabrication. Similarly to the capsid of a virus, VLPs are protein assemblies, but their structural formation, stability, and properties are not fully understood, especially as a function of the protein modifications. In this work, we present a data-driven modeling approach for capturing macromolecular self-assembly on scales beyond traditional molecular dynamics (MD), while preserving the chemical specificity. Each macromolecule is abstracted as an anisotropic object and high-dimensional models are formulated to describe interactions between molecules and with the solvent. For this, data-driven protein–protein interaction potentials are derived using a Kriging-based strategy, built on high-throughput MD simulations. Semi-automatic supervised learning is employed in a high performance computing environment and the resulting specialized force-fields enable a significant speed-up to the micrometer and millisecond scale, while maintaining high intermolecular detail. The reported generic framework is applied for the first time to capture the formation of hepatitis B VLPs from the smallest building unit, i.e., the dimer of the core protein HBcAg. Assembly pathways and kinetics are analyzed and compared to the available experimental observations. We demonstrate that VLP self-assembly phenomena and dependencies are now possible to be simulated. The method developed can be used for the parameterization of other macromolecules, enabling a molecular understanding of processes impossible to be attained with other theoretical models.Publicationtype: Journal ArticleScopus© Citations 2 70 172 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Developmental transformation and reduction of connective cavities within the subchondral boneIt is widely accepted that the subchondral bone (SCB) plays a crucial role in the physiopathology of osteoarthritis (OA), although its contribution is still debated. Much of the pre-clinical research on the role of SCB is concentrated on comparative evaluations of healthy vs. early OA or early OA vs. advanced OA cases, while neglecting how pure maturation could change the SCB’s microstructure. To assess the transformations of the healthy SCB from young age to early adulthood, we examined the microstructure and material composition of the medial condyle of the femur in calves (three months) and cattle (18 months) for the calcified cartilage (CC) and the subchondral bone plate (SCBP). The entire subchondral zone (SCZ) was significantly thicker in cattle compared to calves, although the proportion of the CC and SCBP thicknesses were relatively constant. The trabecular number (Tb.N.) and the connectivity density (Conn.D) were significantly higher in the deeper region of the SCZ, while the bone volume fraction (BV/TV), and the degree of anisotropy (DA) were more affected by age rather than the region. The mineralization increased within the first 250 µm of the SCZ irrespective of sample type, and became stable thereafter. Cattle exhibited higher mineralization than calves at all depths, with a mean Ca/P ratio of 1.59 and 1.64 for calves and cattle, respectively. Collectively, these results indicate that the SCZ is highly dynamic at early age, and CC is the most dynamic layer of the SCZ.Publicationtype: Journal ArticleScopus© Citations 14 513 348 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Tetrabromidocuprates(II)—synthesis, structure and EPR(Multidisciplinary Digital Publishing Institute (MDPI), 2016-04-20); ; ; ; Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separatedparamagneticCu(II)centres. Forthemajorityofcompounds,theprincipalgvalues(g∥ and g⊥) of the tensors could be determined and information on the structural changes in the [CuBr4]2´ anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.Publicationtype: Journal ArticleScopus© Citations 7 256 185 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Enhancement of alkaline protease activity and stability via covalent immobilization onto hollow core-mesoporous shell silica nanospheres(Multidisciplinary Digital Publishing Institute (MDPI), 2016-01-29); ; ; ; The stability and reusability of soluble enzymes are of major concerns, which limit their industrial applications. Herein, alkaline protease from <i>Bacillus</i> sp. NPST-AK15 was immobilized onto hollow core-mesoporous shell silica (HCMSS) nanospheres. Subsequently, the properties of immobilized proteases were evaluated. Non-, ethane- and amino-functionalized HCMSS nanospheres were synthesized and characterized. NPST-AK15 was immobilized onto the synthesized nano-supports by physical and covalent immobilization approaches. However, protease immobilization by covalent attachment onto the activated HCMSS–NH<sub>2</sub> nanospheres showed highest immobilization yield (75.6%) and loading capacity (88.1 μg protein/mg carrier) and was applied in the further studies. In comparison to free enzyme, the covalently immobilized protease exhibited a slight shift in the optimal pH from 10.5 to 11.0, respectively. The optimum temperature for catalytic activity of both free and immobilized enzyme was seen at 60 °C. However, while the free enzyme was completely inactivated when treated at 60 °C for 1 h the immobilized enzyme still retained 63.6% of its initial activity. The immobilized protease showed higher <i>V<sub>max</sub></i>, <i>k<sub>cat</sub></i> and <i>k<sub>cat</sub></i>/<i>K<sub>m</sub></i>, than soluble enzyme by 1.6-, 1.6- and 2.4-fold, respectively. In addition, the immobilized protease affinity to the substrate increased by about 1.5-fold. Furthermore, the enzyme stability in various organic solvents was significantly enhanced upon immobilization. Interestingly, the immobilized enzyme exhibited much higher stability in several commercial detergents including OMO, Tide, Ariel, Bonux and Xra by up to 5.2-fold. Finally, the immobilized protease maintained significant catalytic efficiency for twelve consecutive reaction cycles. These results suggest the effectiveness of the developed nanobiocatalyst as a candidate for detergent formulation and peptide synthesis in non-aqueous media.Publicationtype: Journal ArticleScopus© Citations 56 478 466 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , A novel cyclodextrin glycosyltransferase from alkaliphilic amphibacillus sp. NPST-10 : purification and properties(Multidisciplinary Digital Publishing Institute (MDPI), 2012-08-22); ; ; ; Screening for cyclodextrin glycosyltransferase (CGTase)-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt), resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis<strong> </strong>identified the isolate as <em>Amphibacillus</em><em> </em>sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92 kDa using SDS-PAGE. Catalytic activities of the enzyme were found to be 88.8 U mg<sup>−1</sup> protein, 20.0 U mg<sup>−1</sup> protein and 11.0 U mg<sup>−1</sup> protein for cyclization, coupling and hydrolytic activities, respectively. The enzyme was stable over a wide pH range from pH 5.0 to 11.0, with a maximal activity at pH 8.0. CGTase exhibited activity over a wide temperature range from 45 °C to 70 °C, with maximal activity at 50 °C and was stable at 30 °C to 55 °C for at least 1 h. Thermal stability of the purified enzyme could be significantly improved in the presence of CaCl<sub>2</sub>. <em>K</em><sub>m</sub> and <em>V</em><sub>max</sub> values were estimated using soluble starch as a substrate to be 1.7 ± 0.15 mg/mL and 100 ± 2.0 μmol/min, respectively. CGTase was significantly inhibited in the presence of Co<sup>2+</sup>, Zn<sup>2+</sup>, Cu<sup>2+</sup>, Hg<sup>2+</sup>, Ba<sup>2+</sup>, Cd<sup>2+</sup>, and 2-mercaptoethanol. To the best of our knowledge, this is the first report of CGTase production by <em>Amphibacillus</em> sp. The achieved high conversion of insoluble raw corn starch into cyclodextrins (67.2%) with production of mainly β-CD (86.4%), makes <em>Amphibacillus</em> sp. NPST-10 desirable for the cyclodextrin production industry.Publicationtype: Journal ArticleScopus© Citations 33 474 489