Formation Of Coordination Bonds Research Articles

Versatile BP/Pd-FPEI-CpG nanocomposite for "three-in-one" multimodal tumor therapy

Multimodal nanocatalytic therapy has shown promising potential in cancer treatments. However, to design an effective multimodal nanocatalytic modality, with a deep understanding of synergistic therapy, remains a grand challenge. Herein, we propose an innovative “three-in-one” multimodal strategy with integrated photothermal/photodynamic/chemodynamic modalities for tumor-specific treatment, by rationally constructing a multifunctional two-dimensional (2D) nanoplatform based on the black phosphorous (BP)/Pd nanosheets (NSs) via in-situ growth. Interestingly, such a hybridization of different types of 2D NSs mediates formation of the Pd-P coordination bonds. With strong interfacial Pd-P interaction, the heterostructured NSs display enhanced cascade enzymatic activities in tumor microenvironment, leading to sufficient generation of reactive oxygen species (ROS) as therapeutic species including cytotoxic superoxide (O2•−) radicals by successive catalase-/oxidase-catalysis, and deleterious singlet oxygen (1O2) radicals under light irradiation. The incorporation of Pd also improved the photothermal activity of the material. Furthermore, by facile functionalization with fluoro-polyethyleneimine (FPEI) and loading of cytosine-phosphate-guanine (CpG) as an immune adjuvant, the versatilities of this unique 2D hetero-nanoplatform are further extended, strikingly improving therapeutic efficacy for tumor cells, and simultaneously avoiding significant damage to normal tissues. The work provides useful insights into the design of new 2D nanoplatforms for multimodal tumor treatment.

Solid–Liquid Interfacial Coordination Chemistry Enables High‐Capacity Ammonium Storage in Amorphous Manganese Phosphate

AbstractAmmonium (NH4+) ion as charge carrier is attracting attention in aqueous batteries. Yet, most NH4+ host materials are still limited by the relatively low capacities. Here, we fabricated a manganese phosphate (MP‐20) for NH4+ ion storage. MP‐20 displays a high capacity of 299.6 mAh g−1 at 1 A g−1 in ammonium acetate (NH4Ac) electrolyte, outperforming other reported NH4+ host materials. Spectroscopy studies suggest a new NH4+/H+ co‐insertion mechanism. We surprisingly discover that the NH4Ac electrolyte plays an important role in improving the charge storage capability of the materials. Experimental and computational results indicate acetate ions can form coordination bonds with the Mn atoms, tailoring the electronic structure of the Mn atoms and the surrounding O atoms, and therefore facilitating the NH4+ storage process. Our findings provide a new NH4+ host material and propose the important role of the electrolyte‐electrode coordination effect in aqueous ammonium batteries.

Solid-Liquid Interfacial Coordination Chemistry Enables High-Capacity Ammonium Storage in Amorphous Manganese Phosphate.

Ammonium (NH4 + ) ion as charge carrier is attracting attention in aqueous batteries. Yet, most NH4 + host materials are still limited by the relatively low capacities. Here, we fabricated a manganese phosphate (MP-20) for NH4 + ion storage. MP-20 displays a high capacity of 299.6 mAh g-1 at 1 A g-1 in ammonium acetate (NH4 Ac) electrolyte, outperforming other reported NH4 + host materials. Spectroscopy studies suggest a new NH4 + /H+ co-insertion mechanism. We surprisingly discover that the NH4 Ac electrolyte plays an important role in improving the charge storage capability of the materials. Experimental and computational results indicate acetate ions can form coordination bonds with the Mn atoms, tailoring the electronic structure of the Mn atoms and the surrounding O atoms, and therefore facilitating the NH4 + storage process. Our findings provide a new NH4 + host material and propose the important role of the electrolyte-electrode coordination effect in aqueous ammonium batteries.

Effect of Molecular Weights on Metal-Mediated Grafting of Sulfobetaine Polymers onto Solid Surfaces for Non-Biofouling Applications.

The grafting of zwitterionic molecules onto solid surfaces is an important tool for decreasing the unwanted adsorption of biomolecules, such as proteins, bacteria, and cells. This has been achieved through various approaches, such as zwitterionic monolayer/multilayer formation, surface-initiated polymerization of zwitterionic monomers, and grafting of presynthesized zwitterionic polymers. Recently, a coordination-driven approach to grafting zwitterionic polymers onto solid surfaces has been discovered to be an effective method because of its versatility and robustness. However, the bacterial adhesion resistance of zwitterionic polymer grafting has been explored using only one molecular weight, and the non-biofouling performance against other fouling organisms has remained unexamined. In this study, the characteristics of coordination-driven surface zwitteration are systematically investigated. Sulfobetaine (SB) polymers with three different molecular weights are synthesized and employed for surface grafting. Polydopamine is used as a surface primer, and SB polymers are grafted onto the surfaces via the formation of metal-mediated coordinate bonds. The effect of molecular weight on the grafting efficiency and non-biofouling performance is investigated via protein adsorption and marine diatom adhesion assays. The SB polymer with a high molecular weight is found to be crucial for achieving strong resistance to protein adsorption and marine fouling.

A comparison of the inhibition effect of Zn2+or Fe2+ in the oxidation of [formula omitted]-thiophenol groups in coal

To improve the formulation of high-sulfur coal inhibitor, the inhibition mechanism of Zn2+ and Fe2+ on the α-thiophenol groups in coal was analyzed. The results of natural bond orbital analysis show both Zn2+ and Fe2+ formed coordination bonds with –SH, but the Zn2+ complex was more stable. The activation energy required for the chemical adsorption of O2 on α-thiophenol groups increased by 47.62 kJ/mol due to the influence of Zn2+, which is 12.02 kJ/mol higher than that of the Fe2+ complex. In addition, thermal analysis experiments show 20% ZnCl2 aqueous solution increased the ignition point of Hulusu coal by 27 °C, and the oxidation reaction temperature of various active functional groups increased by 17.3 °C–45.9 °C; FeCl2 only inhibited the functional groups containing O/N/S; and catalyzed the combustion of aliphatic carbon and aromatic carbon skeletons. Therefore, the inhibition effect of Zn2+ was stronger than that of Fe2+.

Integrating a three-dimensional Cu2MoS4 electrode and solid-state polymer electrolyte for sodium-ion batteries

The improvement of solid-state batteries (SSBs) in terms of safety performance and energy density has an unusual significance for it to apply to power batteries, and the interface matching of solid-state electrolytes and adapted electrode materials has become the key. Due to poor electrode-electrolyte interface contact in SSBs which could result in low ionic conductivity, we designed a 3D integrated electrode constructed from a Cu2MoS4 electrode grown in situ on the surface of copper foam with a polymer-in-salt solid electrolyte based on PVDF-HFP. The ion clusters formed by NaPF6 near the PVDF-HFP network structure can effectively shorten the Na+ transport path, and then adding 1-(4-cyanophenyl)-guanidine can also provide more ion transport routes by forming coordination bonds. The polymer electrolyte exhibited excellent ionic conductivity (1.67×10−5 S cm−1 at room temperature) and electrochemical stability (5.6 V vs Na|Na+). At the same time, it showed excellent stability during the cycle performance test of the symmetrical batteries, compared with the liquid electrolytes, the polymer-in-salt solid electrolytes were not short circuit under the same test conditions, indicating that the polymer-in-salt solid electrolytes can effectively inhibit the growth of Na dendrites. This 3D integrated electrode exhibited excellent interface-contact compatibility, mechanical stability, and electrochemical performance closed to that of liquid electrolytes and even outperformed liquid electrolytes at a high rate cycle.

Directed search for diuretics among 6-substituted pteridine-2,4,7(1H,3H,8H)-triones

Directed search for biologically active compounds among heterocycles still remains a relevant area of medical chemistry. Among the significant number of heterocyclic compounds, pteridines deserve special attention. Among the above-mentioned ones the drugs with antitumor, antimicrobial, antiviral, diuretic and other types of biological action are known. Nevertheless, 6-substituted pteridine-2,4,7(1H,3H,8H)-triones, which are structurally similar to triamterene (6-phenylpteridine-2,4,7-triamine) – a diuretic with potassium-sparing action are interesting objects for search for diuretics. All the more, they are characterized by prototropic tautomerism, able to form hydrogen and donor-acceptor bonds with various ligands, and it is likely that these structural features will provide their diuretic effect. The aim of the study is the directed search for diuretics among 6-substituted pteridine-2,4,7(1H,3H,8H)-triones using in silico and in vivo methodology and elucidation of the probable mechanism of action. 1-methyl-3-R-6- (2-oxo-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones were selected to study the effect on renal excretory function. and 1-methyl-3-R-6- (2-hydroxy-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones. Directed search for compounds that affect the excretory function of the kidneys of rats was conducted by the conventional method of E.B. Berkhin with water load. The content of creatinine, sodium, potassium and chlorides in blood and urine plasma was determined by biochemical methods using standard test kits of NPV "Philisit-Diagnostics" (Ukraine) and calculations were performed according to generally accepted methods. Research of the probable mechanism was conducted by flexible molecular docking, as an approach of finding molecules with affinity to a specific biological target. Macromolecular data were downloaded from the Protein Data Bank (PDB) namely, the crystal structures of Human carbonic anhydrase II (PDB ID – 3HS4) and epithelial sodium channel (ENaC) (PDB ID – 4NTX). Studies of the effect of the synthesized compounds on the excretory function of the kidneys of rats showed that 1-methyl-3-R-6- (2-oxo-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones containing 4-fluorophenyl, 2,4-difluorophenyl, 4-chlorophenyl fragments in the molecule increase diuresis by the second hour by 27.3-70.1% compared with the control group. According to the results of the impact on daily diuresis, it was found that the most active was 1-methyl-6- (2-oxo-2-phenyl) ethyl) pteridine-2,4,7(1H,3H,8H)-triones, which increased daily diuresis by 168.1%, exceeding the effect of Hydrochlorothiazide (41.8%) and Triamterene (49.1%). However, substituted 1-methyl-3-R-6- (2-hydroxy-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones are inactive compounds. In-depth studies using biological tests and molecular docking have suggested that 1-methyl-6- (2-oxo-2-aryl) ethyl) pteridine-2,4,7(1H,3H,8H)-triones 2.1, 2.5 and 2.6) probable mechanisms of diuretic action are disruption of sodium transport in the distal convoluted tubules, causing sodium excretion and water loss and possibly inhibition of epithelial sodium channels that promote sodium uptake and potassium secretion in the distal convolutions and tubules, which implements potassium-sparing action. A well-founded and developed strategy for the search for diuretics among 6-substituted pteridine-2,4,7(1H,3H,8H)-triones has identified a number of effective compounds that by diuretic effect are superior to the reference drugs "Hydrochlorothiazide" and "Triamterene". Importantly, the results of molecular docking suggested a mechanism of action of the compounds under study, similar to thiazide diuretics. This action may be related to the tautomerism of these compounds and, as a consequence, their ability to form coordination bonds with the zinc cation and the additional interaction of halogens in the active site of CA II. It was possible to detect the presence of potassium-sparing action, probably due to the ability to inhibit epithelial sodium channels (ENaC). The obtained results substantiate the further purposeful search for potential diuretics among this class of compounds.

Affinity of phenolic compounds for transition metal ions immobilized on cation-exchange columns

Immobilized metal ion affinity chromatography (IMAC) is useful in purification of histidine-tagged or histidine-rich proteins and peptides from a variety of hosts. However, phenolic compounds including polyphenols interfere with IMAC due to their high affinities for the transition metals immobilized on the column resins, which hampers the purification of proteins from plant-based host systems. In contrast to extensive knowledge of the mechanism of the interactions between phenolic compounds and transition metal ions in solution, an understanding of the interactions on the columns, where transition metal ions are immobilized on the resins, remains elusive. This study systematically investigated the affinity of phenolic compounds for transition metal ions by varying the number and position of phenolic hydroxyl groups (OH groups) and using different transition metals—Fe(II), Cu(II) and Ni(II)—on various IMACs, in which the columns were fabricated by equilibrating the cation-exchange column with transition metal solutions. It was found that the more OH groups the aromatic compounds have, the higher the affinity for transition metal ions; in particular, methyl gallate and pyrogallol were permanently bound to the IMAC column, which reflected coordinate bond formation with the transition metal ions. Importantly, the phenolic compounds showed no obvious affinity for the Ni(II)-IMAC column, in contrast to the Fe(II)- and Cu(II)-IMAC columns, whereas imidazole and histidine-tagged proteins showed evident binding to the Ni(II)-IMAC column. Ni(II)-IMAC should thus be especially effective in isolating histidine-tagged and histidine-rich species from phenolic compound-containing systems. These results indicate that the affinity between phenolic compounds and transition metal ions on the column is consistent with the results in solution. They also provide a comprehensive view for devising strategies to improve IMAC purification of target proteins and peptides from samples containing phenolic compounds.

Co-construction of molecular-level uranyl-specific “nano-holes” with amidoxime and amino groups on natural bamboo strips for specifically capturing uranium from seawater

Efficiently capturing of uranium (VI) [U(VI)] from seawater elicits unparalleled attraction for sustaining the uplifted requirement for nuclear fuel. However, obtaining the abundant U(VI) resource from seawater has always seriously restricted by competitive adsorption from higher concentrations of competitors, especially vanadium (V) [V(V)]. Herein, based on amidoximized natural bamboo strips with hierarchical porous structure, the molecular-level uranyl-specific “nano-holes” was co-constructed by the intramolecular hydrogen bonds for specifically trapping U(VI) from seawater. Manipulating the branched degrees of amino groups enabled the creation of a series of the molecular-level uranyl-specific “nano-holes” that exhibit ultrahigh affinity and selective adsorption of U(VI) with a adsorption capacity 1.8 fold higher compared to that of V(V) after 30 days floating in the Yellow Sea basin, conquering the long-term challenge of the competitive adsorption of V(V) for amidoxime-based adsorbents applied to extract U(VI) from seawater. The diameter of the molecular-level uranyl-specific “nano-holes” is approximately 12.07 Å, significantly larger than (UO2)3(OH)3+ (10.37 Å) and smaller than HV10O285-, thereby exhibiting specifically trapping of U(VI) in a series of adsorption experiments with different U(VI)-V(V) ratios. Besides, the adsorption model based on the combination of experimental and theoretical results is accompanied by "hydrogen bond breaking and coordination bond formation".

Learning to Identify Physiological and Adventitious Metal-Binding Sites in the Three-Dimensional Structures of Proteins by Following the Hints of a Deep Neural Network.

Thirty-eight percent of protein structures in the Protein Data Bank contain at least one metal ion. However, not all these metal sites are biologically relevant. Cations present as impurities during sample preparation or in the crystallization buffer can cause the formation of protein–metal complexes that do not exist in vivo. We implemented a deep learning approach to build a classifier able to distinguish between physiological and adventitious zinc-binding sites in the 3D structures of metalloproteins. We trained the classifier using manually annotated sites extracted from the MetalPDB database. Using a 10-fold cross validation procedure, the classifier achieved an accuracy of about 90%. The same neural classifier could predict the physiological relevance of non-heme mononuclear iron sites with an accuracy of nearly 80%, suggesting that the rules learned on zinc sites have general relevance. By quantifying the relative importance of the features describing the input zinc sites from the network perspective and by analyzing the characteristics of the MetalPDB datasets, we inferred some common principles. Physiological sites present a low solvent accessibility of the aminoacids forming coordination bonds with the metal ion (the metal ligands), a relatively large number of residues in the metal environment (≥20), and a distinct pattern of conservation of Cys and His residues in the site. Adventitious sites, on the other hand, tend to have a low number of donor atoms from the polypeptide chain (often one or two). These observations support the evaluation of the physiological relevance of novel metal-binding sites in protein structures.

Kinetics and Adsorption Isotherms of Amine-Functionalized Magnesium Ferrite Produced Using Sol-Gel Method for Treatment of Heavy Metals in Wastewater.

This study is focused on the kinetics and adsorption isotherms of amine-functionalized magnesium ferrite (MgFe2O4) for treating the heavy metals in wastewater. A sol-gel route was adopted to produce MgFe2O4 nanoparticles. The surfaces of the MgFe2O4 nanoparticles were functionalized using primary amine (ethanolamine). The surface morphology, phase formation, and functionality of the MgFe2O4 nano-adsorbents were studied using the SEM, UV-visible, FTIR, and TGA techniques. The characterized nanoparticles were tested on their ability to adsorb the Pb2+, Cu2+, and Zn2+ ions from the wastewater. The kinetic parameters and adsorption isotherms for the adsorption of the metal ions by the amine-functionalized MgFe2O4 were obtained using the pseudo-first-order, pseudo-second-order, Langmuir, and Freundlich models. The pseudo-second order and Langmuir models best described the adsorption kinetics and isotherms, implying strong chemisorption via the formation of coordinative bonds between the amine groups and metal ions. The Langmuir equation revealed the highest adsorption capacity of 0.7 mmol/g for the amine-functionalized MgFe2O4 nano-adsorbents. The adsorption capacity of the nanoadsorbent also changed with the calcination temperature. The MgFe2O4 sample, calcined at 500 °C, removed the most of the Pb2+ (73%), Cu2+ (59%), and Zn2+ (62%) ions from the water.

Self-healable and redox active hydrogel obtained via incorporation of ferric ion for supercapacitor applications

Poly (vinyl alcohol)/phytic acid (PVA/PA) hydrogels have been identified as self-healable electrolytes. In this work, a novel redox active and self-healable PVA/PA/Fe3+ (PPFe) hydrogel containing dual cross-linking network through the formation of both metal coordination bonds and hydrogen bonds was fabricated via a freezing-thawing method. For the first time to our best knowledge, it was found that the introduction of dynamic Fe3+ coordination bonds into the PPFe hydrogel not only improved its mechanical properties and self-healing ability via re-configuration of various bonds, but also afforded the hydrogel high electrochemical redox activity. Compared with plain PVA/PA hydrogels, the as-fabricated PPFe gel delivered greatly improved mechanical properties, including a tensile stress of 0.618 MPa and tensile strain of 924 %, as well as a strain self-healing efficiency of 72 %. The self-healable and redox active PPFe hydrogel was further utilized to fabricate supercapacitors, where the redox reaction of Fe3+ occurred on polyaniline/carbon nanotubes (PANI/CNTs) electro-active material, resulting in an ultra-high 1526 mF/cm2 at 0.5 mA/cm2, and a remarkable energy density of 0.212 mWh/cm2 at 0.25 mW/cm2, as wells as an excellent cycling stability. Moreover, it could recover its electrochemical performance after the cutting-healing, which would greatly improve the reliability and safety of the energy storage device.

Self-healable recyclable thermoplastic polyurethane elastomers: Enabled by metal–ligand bonds between the cerium(III) triflate and phloretin

This study initially developed highly efficient self-healing materials with cerium(III) triflate [Ce(SO3CF3)3] as the metal center and phloretin as the ligand to synthesize a self-healable polyurethane elastomer with excellent self-healable and mechanical properties. Nuclear magnetic resonance data from experimental research on the self-healing mechanism indicated that Ce(SO3CF3)3 and phloretin could effectively form coordination bonds. Then, the hydroxyl group (−OH) on the para position of the phloretin reacted with the isocyanate group in the polyurethane prepolymer to form coordination-bond-facilitated self-healable polyurethane elastomers. An optimal sample (PUPC-2) with high tensile strength (5.17 Mpa) and high stretchability (1,415.7%), ideal toughness (35.08 MJ m−3), and remarkable healing efficiency (near to 100% healed after 48 h at room temperature) was obtained. In addition, the PUPC sample also exhibited good thermoplasticity, which means that the self-healable polyurethane elastomer can be recycled. These excellent performances ensure that the self-healable thermoplastic polyurethane elastomers have a wide range of practical applications. Therefore, a flexible conductive electrode with a self-healable capacity was obtained by compositing the PUPC-2 sample with flexible graphene-based conductive paper, which demonstrated good potential for application in the field of wearable devices and flexible electronics.

Photothermal nanofiller-based polydimethylsiloxane anticorrosion coating with multiple cyclic self-healing and long-term self-healing performance

Self-healing coating is a new strategy for improving the service life of the anticorrosion coating, however, remaining a challenge to achieve stable, multiple cyclic, and long-term self-healing performances of the anticorrosion coating. Herein, a multiple cyclic self-healing and long-term self-healing polydimethylsiloxane coating reinforced by Cu2O@Ag nanofillers was reported. The metal coordination bond, formed between cooper of nanofillers and nitrogen of basal coating, provides good interfacial compatibility between nanofillers and coating, and improve the self-healing performance of the coating for its dynamic reversible process. In addition, the photothermal test indicated that the formation of metal coordination bond improves the photothermal properties and the PDMS-Cu2O@Ag coating had excellent photothermal stability, which provides the possibility of long-term self-healing performance. The scratch and self-healing cyclic tests at the initial stage of immersion and after 80 days of immersion were carried out respectively, which indicated that the coating owned excellent multiple cyclic self-healing and long-term self-healing abilities. Furthermore, the distribution of relaxation time analysis mothed analyzed the anticorrosion process of the coating. The distributions of two kinds of charge transfer processes in the cyclic tests owned different contributions, revealing the anticorrosion mechanism in the self-healing process of the coating. This work would open a new avenue for boosting the multiple cyclic self-healing and long-term self-healing coating performance.

Influence of gas adsorption on the surface photovoltage of Au nanorods embedded polymer coated ZnO nanorods under visible light irradiation

The synergism between the photosensitivity and gas sensitivity enabled the development of low powered highly selective gas sensors. In particular, organic/inorganic hybrid materials contribute to the coupling effect of light activated surface photovoltage modifications. In this report, the effect of visible light and volatile organic compounds (VOCs) on the hybrid sensing layer involving organic/inorganic/noble metal through scanning kelvin probe was disseminated. The sensor was fabricated by spin coating the layer-by-layer assembled poly (allylamine hydrochloride) (PAH) and dextran sulfate (DS) on hydrothermally grown ZnO nanorods followed by the incorporation of gold nanorods on ITO substrates. Structural and optical characterizations revealed the assembly of Au nanorods on the polymer coated ZnO nanorods and maximum absorbance in the visible light region, respectively. The optical nature of the hybrid sensor facilitated significant changes in contact potential difference (CPD) when irradiated with light. Changes in CPD values were measured with respect to alcohol, alkane and amine under illumination. A non-selective interaction was observed, yet the enhanced visible light response to triethylamine (TEA) corresponds to the formation of coordination bonds between the hybrid sensor and adsorbed species. The potential shift of ∼31 mV, ∼67 mV and ∼164 mV were observed for TEA by ZnO, ZnO/Poly and ZnO/Poly/Au, respectively. The simultaneous charge transfer/separation ability, surface plasmon resonance and inhibition of recombination of photogenerted carriers by Au promoted the interaction. Evidence of selective interaction can be elucidated through the selection of different VOCs under specific type of gas for CPD measurements.

Photoredox Processes in the Aggregation and Gelation of Electron-Responsive Supramolecular Polymers Based on Viologen

Viologen-based ditopic bis-pyridinyl-triazole bidentate ligands self-assemble in the presence of palladium ions into supramolecular polymers whose structure is imposed by the directed formation of coordination bonds. Light-irradiation of these electron-responsive supramolecular materials triggers a photo-induced electron transfer yielding isolated π-radicals and dimers of radicals. The photoreduction events and the associated dimerization steps trigger a large-scale reorganization occurring within the supramolecular network yielding aggregates or gels depending on the irradiation conditions (power, duration). Detailed electrochemical, spectro-electrochemical and photochemical analyses were conducted to understand the mechanisms at stakes in these light-induced aggregation and gelation.

A facile and effective immunoassay for sensitive detection of phosphorylated tau: The role of flower-shaped TiO2 in specificity and signal amplification

Alzheimer’s disease (AD) is one of the most prevalent neurodegenerative disease. Plasma total phosphorylated tau (P-tau) with multi-phosphorylation sites is a potentially efficient biomarker for the diagnosis and prognosis of AD. Single phosphorylation site recognition methods lead to the false positive detection of P-tau and decrease the accuracy of AD analysis. In this work, a simple and precise electrochemical immunoassay was developed for the specific detection of P-tau. Calixarene derivative ProLinker was utilized to orient Anti-tau onto the surface of gold electrode. ProLinker provide abundant binding sites for immobilized antibodies via host-guest recognitions and ensure Anti-tau activity through non-covalent interactions. Flower-shaped TiO2 (F-TiO2) forming coordination bonds with the phosphate group of phosphorylated protein were utilized as signal amplification tags to construct a simple sandwich assay for multiple phosphorylated sites sensing of P-tau. The combination of F-TiO2 and Anti-tau ensured the bispecific and precise recognition of P-tau with a wide detection range (1–200 ng/mL) and a low detection of limit (1.774 pg/mL). With large specific surface area, high electron hinder ability, and great stability, F-TiO2 as an amplification molecule can improve the performance of the immunosensor and produce sensitive signal changes according to the concentration of P-tau in the clinical samples. Hence, this P-tau immunoassay paves the way for the development of efficient detection tools for clinical diagnosis and monitoring.

Design and synthesis of iron(II) complexes with Schiff bases derived from 6-aminopenicillanic acid and heterocyclic aldehydes

The reaction of iron (II) acetate with Schiff bases derived from the condensation reaction of benzaldehyde or indole-3-carboxaldehyde with (2S,5R,6R)-6-Amino-3,3-dimethyl-7-oxo-4-thia-1azabi cyclo[3.2.0] hepta -ne-2-carboxylic acid (6- Aminopenicillanic Acid) in 1:1 molar ratio gave a new series of iron(II) complexes. The coordination bond formation behaviour of Schiff bases with iron atom has been characterised by elemental analysis, conductance measurements, molecular weight determinations, IR, UV and 1H NMR spectral studies.

Synthesis and Characterization of New Nanocomposites Based on Montmorillonite and Hexahydroquinolinyl Ether Hybrids

AbstractFamiliarly, montmorillonite (MMT) ‐ based composites are prepared by the absorption method, which produced unstable MMT composites, since the adsorbates were easily pull out from MMT. Herein, using a new technique, the hexahydro‐ quinolinylhexahydroquinolinyl ethers resulting from the cyclization reaction of 1,3‐cyclohexanedione with p‐aminophenol and arylidinemalono‐ nitrilesarylidinemalononitriles in presence of Ca‐montmorillonite (Ca‐MMT), were grafted on Ca‐MMT surface via formation of coordinate bonds to produce stable nanocomposites. In these reactions, Ca‐MMT played as a heterogeneous catalyst and as the hydrophobic surface chemically bonded with the formed ether molecules. NMR, FTIR and XRD analyses confirmed the successful surface modification of the nanoparticles clay with the formed ethers molecules via formation of coordinate and hydrogen bonds. These stable nanocomposites are characterized by their thermal stability and higher solubility in dioxane and dimethyl sulphoxide solvents.Also, these nanocomposites has a potential application in environment, biomedicine and engineered barriers.

G-C3N4/ZnO heterojunction as Fenton-like catalyst for degradation of organic pollution

g-C3N4/ZnO Fenton-like catalysts were prepared by impregnation of g-C3N4 with a solution of zinc nitrate hexahydrate followed by calcination. XRD, FT-IR, XPS, HRTEM, SEM, and other characterization techniques were used to assess the chemical composition, morphology, and structure. The Fenton-like catalytic activity of g-C3N4/ZnO composites was measured in the removal of organic pollutants. The results showed that the g-C3N4/ZnO Fenton-like catalyst can efficiently remove the organic pollutants than pure g-C3N4. The removal efficiency of organic pollutants by g-C3N4/ZnO composite was of 89%, which is 4 times higher than that of pure g-C3N4. This clearly shows a significant improvement in the Fenton-like catalytic activity of g-C3N4/ZnO. This improved result was explained by the production of hydroxyl radicals in the g-C3N4/ZnO-H2O2 catalytic system, in a similar way as in the mechanism involved in the Fenton-like degradation. The formation of coordinate covalent bonds between N and Zn in g-C3N4/ZnO catalyst played an important role in the removal of organic dye, and thus considered another key factor of the excellent activity.