Highly stretchable,self-adhesive,and self-healable double network hydrogel based on alginate/polyacrylamide with tunable mechanical properties

A number of synthetic hydrogels suffer from low mechanical strength. Despite of the recent advances in the fabrication of tough hydrogels, it is still a great challenge to simultaneously construct high stretchability, and self-adhesive and self-healing capability in a hydrogel. Herein, a new type of double network hydrogel was prepared based on irreversible cross-linking of polyacrylamide chains and Schiff-base reversible cross-linking between glycidyl methacrylate-grafted ethylenediamine and oxidized sodium alginate (OSA). The combination of both cross-linkings and their synergistic effect provided a novel hydrogel with high strength, stretchable, rapid self-healing, and self-adhesiveness to different material. Besides, the hydrogels with diverse OSA content could maintain their original shapes after loading–unloading tensile test. The resulting hydrogel has a great potential in various fields for supporting and load-bearing substance.     

Synthesis,Hirshfeld surface analysis,luminescence and thermal properties of three first-row transition metal complexes containing 4′-hydroxy-2,2′:6′,2″-terpyridine: Application for preparation of nano metal oxides

A series of new mono- and bis-terpyridine complexes [Mn(tpyOH)Cl₂] ( 1 ), [Ni(tpyOH)₂](PF₆)₂ ( 2 ) and [Zn(tpyO)(η¹-OCOCH₃)(H₂O)]⋅3H₂O ( 4 ) containing 4′-hydroxy-2,2′:6′,2″-terpyridine (tpyOH) were synthesized and structurally characterized using elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The reaction of MnCl₂ with tpyOH in a mixture of methanol and CH₂Cl₂ resulted in the formation of 1 . The X-ray crystal structure of 1 reveals that Mn(II) is penta-coordinated by three nitrogen atoms from tpyOH and two Cl⁻ in a slightly distorted trigonal bipyramidal geometry. Complex 2 was also prepared by the reaction of nickel(II) chloride with tpyOH in a methanolic medium in the presence of NH₄PF₆. Notably, the complex [Ni(tpyOH)(tpyO)]PF₆ ( 3 ), obtained during the crystallization of 2 from dichloromethane, was characterized using X-ray crystallography which shows that six nitrogen atoms from terpyridine ligands occupy the coordination sites around the Ni(II) centre in a distorted octahedral geometry with four longer bonds and two shorter Ni N bonds. The reaction of zinc(II) acetate with tpyOH in a mixture of methanol and CH₂Cl₂ led to the formation of 4 . The crystal structure of 4 reveals the formation of penta-coordinated Zn(II) complex containing three nitrogen atoms from tpyO, a monodentate acetate ligand and one coordinated water molecule. Hirshfeld surface analyses and two-dimensional fingerprint plots show that the main interactions are O…H/H…O contacts in 1 , 3 and 4 . The thermal decomposition reactions of 1 , 2 and 4 were studied using thermogravimetric analysis in detail due to their different structures. The solution luminescence features of 1 , 2 and 4 include high-energy intense π → π* intraligand and low-energy metal-to-ligand charge transfer transitions at room temperature. The calcination of the coordination complexes led to the formation of corresponding nano metal oxides. The products were structurally characterized using infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The average particle size using Scherrer's equation was calculated to be below 50 nm.     

Direct oxidative synthesis of nitrones from aldehydes and primary anilines using graphite oxide and Oxone

One-pot condensation/oxidation of aldehydes and primary anilines into nitrones using graphite oxide (GO) and Oxone as the oxidant under very mild reaction conditions is described. The proposed method provides a direct oxidative synthesis of various nitrones in good to excellent yields under metal-free conditions in short reaction times.     

Characterization and performance of Pd/Ni(Zn)-aluminate catalysts for acetylene hydrogenation

Research on Chemical Intermediates - 0.03 wt% Pd catalysts on nickel and zinc aluminate supports were prepared by impregnation. The samples were characterized by XRD, BET, ICP, SEM, EDS,...     

Synthesis of a new Pt(II) complex containing valganciclovir drug and calf-thymus DNA interaction study using multispectroscopic methods

A new complex, [Pt(valcyte)(DMSO)Cl]Cl, in which valcyte (trade name) served as valganciclovir hydrochloride drug ([2-[(2-amino-6-oxo-3H-purin-9-yl)methoxy]-3-hydroxypropyl](2S)-2-amino-3-methylbutanoate), was synthesized and characterized by different physicochemical methods. Binding interaction of this complex with calf-thymus DNA (ct-DNA) has been investigated by multispectroscopic techniques. The complex displays significant binding properties with ct-DNA. The results of fluorescence and UV–vis absorption spectroscopy indicated that this complex interacted with ct-DNA in a groove-binding mode, and the binding constant was 3.8 × 10⁴ M^?1. Furthermore, the complex induced detectable changes in the CD spectrum of ct-DNA and slightly changed its viscosity which verified the groove-binding mode. Finally, all results indicated that Pt(II) complex interact with DNA via groove-binding mode.     

Determination of gold in water samples using electromembrane extraction

In this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5?µg L^?1 (S/N?=?3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples.     

On-line packed magnetic in-tube solid phase microextraction of acidic drugs such as naproxen and indomethacin by using Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>@SiO<Subscript>2</Subscript>@layered double hydroxide nanoparticles with high anion exchange capacity

The authors describe a 3-component nanoparticle system composed of a silica-coated magnetite (Fe₃O₄) core and a layered double (Cu-Cr) hydroxide nanoplatelet shell. The sorbent has a high anion exchange capacity for extraction anionic species. A simple online system, referred to as "on-line packed magnetic-in-tube solid phase microextraction" was designed. The nanoparticles were placed in a stainless steel cartridge via dry packing. The cartridge was then applied to the preconcentration acidic drugs including naproxen and indomethacin from urine and plasma. Extraction and desorption times, pH values of the sample solution and flow rates of sample solution and eluent were optimized. Analytes were then quantified by HPLC with UV detection. Under optimal conditions, the limits of detection range from 70 to 800 ng L^?1, with linear responses from 0.1–500 μg L^?1 (water samples), 0.6–500 μg L^?1 (spiked urine), and 0.9–500 μg L^?1 (spiked plasma). The inter- and intra-assay precisions (RSDs, for n?=?5) are in the range of 2.2–5.4%, 2.8–4.9%, and 2.0–5.2% at concentration levels of 5, 25 and 50 μg L^?1, respectively. The method was applied to the analysis of the drugs in spiked human urine and plasma, and good results were achieved.

Open image in new window

Graphical abstract Fe₃O₄@SiO₂@CuCr-LDH magnetic nanoparticles were synthesized and packed in to a stainless steel column. The column was applied to solid phase microextraction of acidic drugs from biological samples.

     

Sensitive electrochemical DNA-based biosensors for the determination of Ag<Superscript>+</Superscript> and Hg<Superscript>2+</Superscript> ions and their application in analysis of amalgam filling

In the present paper, we used single-stranded poly-T (100% thymine bases) and poly-C (100% cytosine bases) nucleic acids as DNA probes for selective and sensitive individual electrochemical determination of Hg²⁺ and Ag⁺_, respectively, on the multi-walled carbon nanotube paste electrodes (MWCNTPEs) using [Fe(CN)₆]^3?/4? as electroactive labels. In the presence of Hg²⁺ and Ag⁺, the probe–Hg²⁺/Ag⁺ interactions through T–Hg²⁺–T and C–Ag⁺–C complexes formation could cause the formation of a unimolecular hybridized probe. This structure of probe led to its partial depletion from electrode surface and facilitation of electron transfer between [Fe(CN)₆]^3?/4? redox couple and electrode surface, resulting in the enhanced differential pulse voltammetry (DPV) oxidation current of [Fe(CN)₆]^3?/4? at the probe-modified electrode surface. We applied the difference in the oxidation peak currents of [Fe(CN)₆]^3?/4? before and after Hg²⁺/Ag⁺–DNA probe bonding (?I) for electrochemical determination of these heavy metal ions. Detection limits were 8.0?×?10^?12 M and 1.0?×?10^?11 M for Hg²⁺ and Ag⁺ ions determination, respectively. The biosensors were utilized to determine the weight percent of toxic metals, i.e., silver and mercury in dental amalgam filling composition. The results of their practical applicability in analysis of the amalgam sample were satisfactory.     

Computational explorations to gain insight into the structural features of TNF-α receptor I inhibitors

TNF-α is a crucial cytokine in the process of inflammatory diseases. The adverse effect of TNF-α is mostly mediated by interaction of TNF-α with TNF-α receptor type I (TNFR1); therefore, discovery of molecules which can bind to TNFR1 preventing TNF-α-receptor complex formation would be of great interest. In the current study, using GRID/GOLPE program, a 3D-QSAR study was conducted on a series of synthetic TNFR1 binders, which resulted in a 3D-QSAR model with appropriate power of predictivity in internal (r²?=?0.94 and q²_LOO?=?0.74) and external (r²?=?0.66 and SDEP?=?0.42) validations. The structural features of TNFR1 inhibitors essential for exerting activity were explored by analyzing the contour maps of the 3D-QSAR model showing that steric interactions and hydrogen bonds are responsible for exerting TNFR1 inhibitory activity. To propose potential chemical entities for TNFR1 inhibition, PubChem database was searched and the selected compounds were virtually tested for anti-TNFR1 activity using the generated model, resulting in two potential anti-TNFR1 compounds. Finally, the possible interactions of the compounds with TNFR1 were investigated using docking studies. The findings in the current work can pave the way for designing more potent anti-TNFR1 inhibitors.     

Noscapine-derived β-amino alcohols as new organocatalysts for enantioselective addition of diethylzinc to aldehydes

In this paper, synthesis of two derivatives of noscapine and their application as organocatalysts in the asymmetric addition of diethylzinc to aromatic aldehydes is reported. The first catalyst (2) was synthesized by the reduction of lactone ring of noscapine to form the corresponding diol, and the second one (3) was prepared by tert-butyl dimethyl silylation of the primary hydroxyl group of 2. Excellent yields and high ees up to 95% were obtained by using 3 as the catalyst. To the best of our knowledge, this is the first report on the application of lactone ring opened noscapinoid compounds as organocatalysts in asymmetric reactions.