The Sub-picomolar Cu2+ Dissociation Constant of Human Serum Albumin

The apparent affinity of human serum albumin (HSA) for divalent copper has long been the subject of great interest, due to its presumed role as the major Cu²⁺-binding ligand in blood and cerebrospinal fluid. Using a combination of electronic absorption, circular dichroism and room-temperature electron paramagnetic resonance spectroscopies, together with potentiometric titrations, we competed the tripeptide GGH against HSA to reveal a conditional binding constant of log ^c =13.02±0.05 at pH 7.4. This rigorously determined value of the Cu²⁺ affinity has important implications for understanding the extracellular distribution of copper.     

Biobased Polyurethane Composite Foams Reinforced with Plum Stones and Silanized Plum Stones

In the following study, ground plum stones and silanized ground plum stones were used as natural fillers for novel polyurethane (PUR) composite foams. The impact of 1, 2, and 5 wt.% of fillers on the cellular structure, foaming parameters, and mechanical, thermomechanical, and thermal properties of produced foams were assessed. The results showed that the silanization process leads to acquiring fillers with a smoother surface compared to unmodified filler. The results also showed that the morphology of the obtained materials is affected by the type and content of filler. Moreover, the modified PUR foams showed improved properties. For example, compared with the reference foam (PUR_REF), the foam with the addition of 1 wt.% of unmodified plum filler showed better mechanical properties, such as higher compressive strength (~8% improvement) and better flexural strength (~6% improvement). The addition of silanized plum filler improved the thermal stability and hydrophobic character of PUR foams. This work shows the relationship between the mechanical, thermal, and application properties of the obtained PUR composites depending on the modification of the filler used during synthesis.     

Physico-chemical and proteolytic changes during cold storage of dry-cured pork loins with probiotic strains of LAB

Selected physico-chemical and proteolysis-related parameters were evaluated in dry-cured loins inoculated with probiotic (Lactobacillus rhamnosus LOCK900, Bifidobacterium animalis subsp. lactis BB12) and potentially probiotic (Lactobacillus acidophilus Bauer Ł0938) lactic acid bacteria (LAB) strains and compared with a control sample at five different storage times (28, 90, 180, 270 and 360 days). Physico-chemical parameters of dry-cured loins were significantly (P < 0.01) affected by treatment, storage time and the interaction between them. The count of lactic acid bacteria (LAB) in dry-cured loins was in accordance with their pH. Higher intensity of proteolysis, as assessed by non-protein nitrogen content (NPN) and proteolysis index (PI), occurred in inoculated samples. Based on the SDS-PAGE analysis, the modifications produced during storage on the sarcoplasmic proteins were more pronounced than those exerted on the myofibrillar protein fraction. However, inoculation effect was absent from SDS-PAGE protein patterns.     

New calcium‐free Na2O–Al2O3–P2O5 bioactive glasses with potential applications in bone tissue engineering

Sodium aluminophosphate glasses were evaluated for their bone repair ability. The glasses belonging to the system 45Na₂O–xAl₂O₃‐(55‐x)P₂O₅, with x = (3, 5, 7, 10 mol%) were prepared by a melt‐quenching method. We assessed the effect of Al₂O₃ content on the properties of Na₂O–Al₂O₃–P₂O₅ (NAP) glasses, which were characterized by density measurements, DSC analyses, solubility, bioactivity in simulated body fluid and cytocompatibility with MG‐63 cells. To the best of our knowledge, this is the first investigation of calcium‐free Na₂O–Al₂O₃–P₂O₅ system glasses as bioactive materials for bone tissue engineering.     

Biomimetic in situ nucleation of calcium phosphates by protein immobilization on high strength ceramic materials

Zirconia has been commonly used in the dental industry because of its excellent biological, mechanical and aesthetic properties. This material, however, is classified as nearly inert. To bioactivate the ceramic surface, biomimetic depositions of calcium phosphate coatings have been developed. We demonstrate an accelerated biomimetic coating method on zirconia using a specific pre-treatment with biological agents. We have chosen bovine serum albumin as a standard protein. Through the pre-treatment of the zirconia using a hydroxylation or additionally immobilizing the bovine serum albumin on the surface, we could influence the CaP deposition rate. Immunohistochemical analyses verified the presence of BSA on the zirconia surfaces. After immersion in simulated body fluid at 40 °C, the samples were analyzed by scanning electron microscopy and X-ray diffraction to visualize the CaP formation. Here we could show as proof-of-principle that it is possible to accelerate biomimetic coating processes on zirconia implants containing BSA on their surface.     

Synthesis,characterization and application of a novel zinc(II) ion-imprinted polymer

In our study, a Zn(II) ion-imprinted polymer (ZnIP) and non-imprinted polymer (NIP) were synthesized via free-radical polymerization. 1-Vinylimidazole, ethylene glycol dimethacrylate, 2-hydroxyethylmethacrylate and 2,2′-azobisisobutyronitrile were used as functional, cross-linking monomers and free-radical initiator, respectively. The obtained polymer was characterized by various analytical methods (Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, Wavelength Dispersive X-ray Fluorescence, UV VIS, thermal analysis). The sorption properties of ZnIP and NIP were evaluated after removal of Zn(II) ions from the polymer network. The optimum pH for adsorption was 7.0. The maximum adsorption capacity at the pH was 5.2 and 0.22 mg/g for ZnIP and NIP, respectively. To determine the selectivity, the polymer was equilibrated with the binary mixture of Zn(II) ions and the interfering ions [Cu(II), Ni(II) or Co(II)]. The relative selectivity of ZnIP was 22.57, 5.44 and 46.17 for Cu(II), Ni(II) and Co(II) ions, respectively. The proposed ZnIP sorbent was applied to determine the zinc ions in urine samples by Wavelength Dispersive X-ray Fluorescence.     

HDS and HDN activity of molybdenum and nickel–molybdenum catalysts supported on alumina–titania carriers

Alumina–titania supports containing 5–50 wt.% of TiO₂ were prepared by coprecipitation method using inorganic precursors (sodium aluminate and titanium chloride). DTA-TGA, XRD, SEM, TPD_NH3, and IR spectroscopy were used to characterise these materials. The study shows that the promoting effect of nickel on the HDS activity of molybdenum catalysts supported on Al₂O₃TiO₂ is significantly lower than that for molybdenum catalyst supported on Al₂O₃, and depends on the TiO₂ content. The SEM results show that in the case of rich Al support (20 wt.% of TiO₂) molybdenum was aggregated on the external surface of the catalyst, whereas it was uniformly dispersed on the external surface of alumina. Results also show that molybdenum is preferably supported on aluminum oxide. Application of Al₂O₃TiO₂ oxides enhances the HDN activity of nickel–molybdenum catalysts. The highest HDN efficiency was obtained for the NiMo/Al₂O₃TiO₂ catalyst containing 50 wt.% of TiO₂. HDN activity was found to depend on protonic acidity and anatase content.     

Cathodic activation of synthesized highly defective monoclinic hydroxyl-functionalized ZrO2 nanoparticles for efficient electrochemical production of hydrogen in alkaline media

The high electrochemical stability of Zirconia (ZrO₂) at high potentials strongly suggested it as an alternative to carbon supports, which experience reduced efficiency due to some corrosion problems particularly during prolonged electrocatalysis activity. However, the use of ZrO₂ was limited by its low electrical conductivity and surface area. In this work, we developed a methodology for synthesizing monoclinic ZrO₂ NPs with increased surface area and improved electrical/electrocatalytic characteristics without using any carbon-based co-support material or any metallic nanoparticles. In this context, for the first time, highly defective hydroxyl-functionalized ZrO₂ NPs (designated here as ZT NPs) were prepared by a hydrothermal route in the presence of sodium tartrate as a mineralizer. XRD analysis demonstrated that the produced zirconia was semicrystalline microspheres, consisting of monoclinic ZrO₂ NPs with high lattice defects. The addition of tartrate ions decreased the crystallite size and increased the defects and microstrain. At the same time, the alkaline hydrogen evolution reaction (HER) catalytic activity of ZrO₂ NPs was significantly increased when using sodium tartrate as mineralizer; the overpotential required to obtain 10 mA cm⁻² (η₁₀) dropped down from 490 to merely 235 mV, while an exchange current density (j_o) increased 12 times to 0.22 mA cm⁻². The presence of structural defects (revealed by XRD) and the increased number of active surface sites contending O-H groups (evidenced from ATR-FTIR and XPS) as well as the enhanced electrochemical active surface area (confirmed from double-layer capacitance measurements) were the main reasons behind the high catalytic performance. The ZrO₂ NPs catalytic activity increased even further during the long-term stability tests under severe cathodic conditions (ZT*, ZrO₂ NPs obtained after the long-term stability, has j_o = 0.47 mA cm⁻² and η₁₀ = 140 mV), approaching the activity of Pt/C catalyst. This process was assisted by mineralizer removal from the catalyst (testified by XPS). Our studies revealed that ZT* are characterized by larger electroactive surface area and more structure defects compared to ZT, where surface area and microstrains resulting from surface hydroxylation open cavities in zirconia structure.     

Water vapour adsorption properties of agglomerated baby food powders

This paper presents an analysis of the physical properties of materials in powder and agglomerate form and their sorption characteristics on the basis of the shape of the water vapour adsorption isotherms and kinetics. The observed changes that led to a decrease in the vapour adsorption ability of the investigated powdered baby foods depended mainly on their milk powder content and to a lesser extent on the structure of the powders. This was related to the process of agglomeration and the type of wetting liquid used in that process. Wet agglomeration of the baby food powders investigated in this study influenced growth of particle size and increased wettability regardless of the type of wetting liquid used and the components of the powders. The agglomerates obtained using 2% lecithin solution or 50% sugar solution as the wetting liquids presented a decrease in their rate of water adsorption compared to the agglomerates obtained using water.