Non-Covalent Synthesis of Metal Oxide Nanoparticle–Heparin Hybrid Systems: A New Approach to Bioactive Nanoparticles

Heparin has been conjugated to Fe₃O₄, Co₃O₄, and NiO nanoparticles (NPs) through electrostatic interactions, producing colloidal suspensions of hybrid metal oxide heparin NPs that are stable in water. Negative zeta potentials and retention of heparin’s ability to capture toluidine blue indicate that heparin’s negative charges are exposed on the surface of the coated NPs. IR results confirmed the formation of nanohybrids as did NMR experiments, which were also interpreted on the basis of toluidine blue tests. Transmission electron microscopy results revealed that the heparin coating does not modify the shape or dimension of the NPs. Dynamic light scattering and negative zeta potential measurements confirmed that heparin surface functionalisation is an effective strategy to prevent NP aggregation.     

Structure–property relationships in BaTiO3–BiFeO3–BiYbO3 ceramics

Ba_1?xBi_xTi_1?xYb_x/2Fe_x/2O₃ ceramics were fabricated by the solid state reaction method. X-ray diffraction analyses show 0 ≤ x ≤ 0.04 ceramics to have an average crystal structure described by the non-centrosymmetric tetragonal P4 mm space group, whereas x ≥ 0.08 ceramics are consistent with a centrosymmetric cubic perovskite (space group Pm-3 m). Coexistence of both tetragonal and cubic symmetries is observed for x = 0.06. Raman spectroscopy analysis corroborate a change in average structure with increasing x, but also show the local crystal symmetry for x ≥ 0.08 ceramics to deviate from the idealized cubic perovskite structure. Dielectric data show a ferroelectric-to-relaxor crossover, which occurs in conjunction with the change in both the average and local crystal symmetry as indicated by X-ray and Raman data. For x ≥ 0.08, ceramics exhibit relaxor behavior, which is also accompanied by a shift of the permittivity maxima towards higher temperatures with increasing x.     

Direct Regio‐, Diastereo‐, and Enantioselective Vinylogous Michael Addition of Prochiral 3‐Alkylideneoxindoles to Nitroolefins

3‐Alkylidene‐2‐oxindoles represent a simple, yet enabling subfamily of indole alkaloids, and their ability to react as electron‐poor acceptors has largely been investigated. In contrast, their utility as pronucleophilic synthons remains elusive. In this context, the present article describes the successful execution of the direct, organocatalytic asymmetric Michael addition of prochiral 3‐alkylideneoxindoles to nitroolefins. A variety of γ‐substituted alkylideneoxindoles carrying two stereocenters at both the γ‐ and δ‐carbon sites was assembled with excellent stereoselectivity and without olefin isomerization or stereochemical ablation.     

Immiscible PHB/PBS and PHB/PBSA blends: morphology,phase composition and modelling of elastic modulus

This paper reports the thermal, morphological and mechanical properties of environmentally friendly poly(3-hydroxybutyrate) (PHB)/poly(butylene succinate) (PBS) and PHB/poly[(butylene succinate)-co-(butylene adipate)] (PBSA) blends, prepared by melt mixing. The blends are known to be immiscible, as also confirmed by the thermodynamic analysis here presented. A detailed quantification of the crystalline and amorphous fractions was performed, in order to interpret the mechanical properties of the blends. As expected, the ductility increased with increasing PBS or PBSA amount, but in parallel the decrease in the elastic modulus appeared limited. Surprisingly, the elastic modulus was found properly described by the rule of mixtures in the whole composition range, thus attesting mechanical compatibility between the two blend components. This unusual behavior has been explained as due to co-continuous morphology, present in a wide composition range, but also at the same time as the result of shrinkage occurring during sequential crystallization of the two components, which can lead to physical adhesion between matrix and dispersed phase. For the first time, the elastic moduli of the crystalline and mobile amorphous fractions of PBS and PBSA and of the mobile amorphous fraction of PHB at ambient temperature have been estimated through a mechanical modelling approach. © 2021 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.     

Urolithin as a converging scaffold linking ellagic acid and coumarin analogues: design of potent protein kinase CK2 inhibitors

Casein kinase 2 (CK2) is a ubiquitous, essential, and highly pleiotropic protein kinase; its abnormally high constitutive activity is suspected to underlie its pathogenic potential in neoplasia and other relevant diseases. Previously, using different in silico screening approaches, two potent and selective CK2 inhibitors were identified by our group: ellagic acid, a naturally occurring tannic acid derivative (K(i)=20 nM) and 3,8-dibromo-7-hydroxy-4-methylchromen-2-one (DBC, K(i)=60 nM). Comparing the crystallographic binding modes of both ellagic acid and DBC, an X-ray structure-driven merging approach was taken to design novel CK2 inhibitors with improved target affinity. A urolithin moiety is proposed as a possible bridging scaffold between the two known CK2 inhibitors, ellagic acid and DBC. Optimization of urolithin A as the bridging moiety led to the identification of 4-bromo-3,8-dihydroxy-benzo[c]chromen-6-one as a novel, potent and selective CK2 inhibitor, which shows a K(i) value of 7 nM against the protein kinase, representing a significant improvement in affinity for the target compared with the two parent fragments.     

An Easy Entry to Optically Active Spiroindolinones: Chiral Brønsted Acid‐Catalysed Pictet–Spengler Reactions of Isatins

The first catalytic asymmetric Pictet–Spengler reaction of isatins is presented. BINOL‐derived phosphoric acids were found to be competent catalysts for this transformation, giving challenging spirooxindole structures bearing a quaternary stereocentre with generally good results. The 1,2,3,4‐tetrahydro‐β‐carboline products (spiroindolinones) are the core of some newly discovered anti‐malarial agents.     

Crosslinking kinetics of SBR composites containing vulcanized ground scraps as filler

The aim of this study was to characterize the cure reaction of styrene–butadiene rubber (SBR) composites containing industrial rubber scraps. Different proportions of SBR ground scraps (SBR-r), varying from 10 to 80 parts per hundred of rubber, were incorporated into a base formulation of identical composition. Crosslink formation and the kinetics of the cure reaction were evaluated through oscillatory disk rheometry, differential scanning calorimetry, and crosslink density. Cure characteristics, such as scorch time and cure time, decreased with increasing SBR-r content. Minimum torque indicated only a small variation in the viscosity with the incorporation of SBR-r. The maximum torque decreased with the addition of scrap rubber, as a consequence of the reduction in virgin rubber content where crosslinks had been formed. Crosslink density values corroborated these findings, presenting a slight decrease with the increase in the SBR-r content. The kinetic study indicated lower enthalpy values for SBR-r composites compared to those of the control sample. The kinetic parameters, such as activation energy and reaction order, indicated a change in the mechanism of reaction, related to the increased complexity of the systems.     

Fibers based on cellulose‐chitin blends

Fibers made of cellulose (CE) and chitin (CH) in different proportion were wet spun from solutions in dimethylacetamide containing 5% LiCl (w/w). Polymer concentration was purposely maintained as low as possible (?2.4% w/w). Moreover, dope temperature was 60°C to have good spinability. Comparison of the elastic modulus (E) of fibers “as spun” at different CE/CH ratio showed a synergy between the components: at CE/CH ? 50/50, E is ?15 GPa with respect to ?9 and ?11 GPa for neat CE and CH fibers, respectively. Application of a pull‐off ratio during the coagulation allows the E value to increase further. These results, as well as the electronic microscopy of fibers section, agree with a complete miscibility of two polymers at the solid state, probably enhanced by the presence of LiCl. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1825–1831, 2002     

Asymmetric Dimethylarginine Plasma Levels and Endothelial Function in Newly Diagnosed Type 2 Diabetic Patients

It is now well established that major risk factors for cardiovascular diseases (CVD) impact upon endothelial function by decreasing nitric oxide (NO) bioavailability. Asymmetric dimethylarginine (ADMA), an endogenous analog of l-arginine, is able to inhibit the activity of endothelial-NO synthase, promoting endothelial dysfunction. Type 2 diabetes (T2D) is characterized by a reduced endothelium-dependent vasodilation and increased ADMA levels and ADMA is strongly associated with micro- and macrovascular diabetic complications. However, there are not a lot of data about the role of ADMA on endothelial function in newly diagnosed T2D patients without cardiovascular (CV) complications. For this aim, we have enrolled forty-five newly diagnosed T2D patients, evaluated by a oral glucose tolerance test, and thirty normal subjects. Endothelium-dependent and -independent vasodilatation was investigated by intra-arterial infusion of increasing doses of acetylcholine (ACh) and sodium nitroprusside. ADMA was measured by high-performance liquid chromatography and insulin resistance (IR) by HOMA. Newly diagnosed T2D patients showed higher ADMA and l-arginine mean values in comparison with normal subjects and a significantly reduced ACh-stimulated forearm blood flow (FBF). In T2D patients FBF was significantly and inversely correlated with ADMA (r = −0.524, p < 0.0001) and in a multivariate regression analysis, ADMA resulted the stronger predictor of FBF, explaining the 27.5% of variability (p < 0.0001). In conclusion, ADMA was strongly related to endothelial dysfunction also in patients with newly diagnosed T2D, without clinically manifest vascular complications. This field is of great interest for understanding the mechanisms underlying the pathogenesis of diabetic disease and its CV complications.