Self-assembled nanozyme complexes with enhanced cascade activity and high stability for colorimetric detection of glucose

In this work, a hybrid multi-enzyme system, CeO₂/glucose oxidase (GOx) nanocomplex was developed via self-assembly and exhibited excellent catalytic activity toward cascade reactions, offering a simple and efficient example to build spatially confined multi-enzyme systems to potentiate their applications in energy conversion, detoxification and bioanalysis.     

Syntheses and crystal structures of two Schiff-base copper(II) complexes with urease inhibition

Two new copper(II) complexes, [CuL1(N₃)] (1) and [CuL2(NCS)] (2) (HL1 = 4-chloro-2-[(2-piperidin-1-ylethylimino)methyl]phenol, HL2 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an azide coordinated mononuclear complex, while complex 2 is a terminal thiocyanate coordinated mononuclear complex. The coppers in both complexes are four-coordinate, square-planar. Both complexes show potent urease inhibitory properties.     

Phenyltetraene-based nonlinear optical chromophores with enhanced chemical stability and electrooptic activity

"Push-pull" phenyltetraene-based chromophores are too sensitive to be incorporated into Diels-Alder-type cross-linkable polymers due to the reactivity of its diene segment with maleimides. A facile synthetic route has been explored to incorporate a methoxy group into the R position of such chromophores, which reduces their diene reactivity during the poling and lattice hardening process. The poled polymers with one of such chromophores doped in a cross-linked polymer lattice showed ultrahigh electro-optic activities, up to 306 pm/V at 1310 nm.     

Synthesis of an immunologically active fragment analog of prothymosin alpha with enhanced enzymatic stability

A fragment analog, [D-Arg30]prothymosin alpha fragment 1-30, containing D-arginine in place of arginine residue at position 30 was synthesized by the liquid phase procedure and studied for immunological effect on the impaired blastogenic response of T-lymphocytes isolated from uremic patients after treatment of human serum. Deacetyl-thymosin alpha 1, a synthetic octaeicosapeptide corresponding to deacetyl-prothymosin alpha fragment 1-28, has restoration ability for the impaired blastogenic response of T-lymphocytes of uremic patients but is susceptible to proteolytic digestion. On the other hand, the fragment analog, [D-Arg30]prothymosin alpha fragment 1-30 retained activity and was shown to exhibit a high degree of stability when incubated in human serum. These results indicate that N-terminal acetylation and the introduction of D-residue into the C-terminal residue of prothymosin alpha fragment 1-30 increase resistance to proteolytic degradation by exopeptidases.     

Thermal stability of some azo-derivatives and their complexes

this paper deals with the first investigation concerning the thermal stability of two 1-(2-benzothiazolyl)-3-methyl-4-azo-pyrazil-5-one derivatives and their Cu(II) coordination compounds of type ((C₄H₉)₄N)₂[Cu(L)₂]. The thermal decomposition steps were established. This revised version was published online in July 2006 with corrections to the Cover Date.     

Encapsulation of single enzyme in nanogel with enhanced biocatalytic activity and stability

Single protein encapsulated into nanogels with uniformed size and controllable shell thickness were prepared by surface acryloylation of a protein molecule followed by aqueous in situ polymerization. Compared to its free counterpart, the encapsulated protein exhibits similar biocatalytic behavior and significantly improved stability at high temperature and in the presence of organic solvent.     

Reduced Ti-MOFs encapsulated black phosphorus with high stability and enhanced photocatalytic activity

The generation of green hydrogen(H_2) energy is of great significance to solve worldwide energy and environmental issues. Reduced Ti based photocatalyst has recently attracted intensive attention due to its excellent photocatalytic activity, while the synthesis of reduced Ti based photocatalysts with high stability is still a great challenge. Here, we report a facile method for synthesis of reduced Ti metal organic frameworks(small amounts of Pt incorporated) encapsulated BP(BP/R-Ti-MOFs/Pt) hybrid nanomaterial with enhanced photocatalytic activity. The strong interaction between Ti and P reduces the valence state of the binding Ti⁴⁺on the BP surface, forming abundant reduced Ti⁴⁺within R-Ti-MOFs/BP. Such reduced Ti⁴⁺render R-Ti-MOFs/BP efficient charge transfer and excellent light absorption capability, thus promote the photocatalytic H_2 production efficiency. Furthermore, the Ti-P interaction stabilizes both reduced Ti⁴⁺and BP during the photocatalytic reaction, which greatly enhanced the stability of the obtained BP/R-TiMOFs/Pt photocatalyst.     

Oxovanadium(IV) based hypocrellin B complexes with enhanced photodynamic activity

Hypocrellin B (HB), a naturally occurring photosensitizer, has been extensively and intensively studied as a promising photodynamic therapy (PDT) agent. In this work, three new oxovanadium(IV) complexes were designed and synthesized with HB as a bridging ligand and phen (1,10-phenanthroline, complex 1), tmp (3,4,7,8-tetramethyl-1,10-phenanthroline, complex 2) and dpq (dipyrido[3,2-f:2'3'-h]quinoxaline, complex 3) as terminal ligands. The use of a diimine terminal ligand avoids the formation of polymeric complexes and ensures the three VO(2+)-HB complexes possess a definite molecular formula and molecular weight to meet the single component requirement for an ideal PDT agent. Compared to HB, the VO(2+)-HB complexes exhibit improved water solubility, enhanced absorptivity in the phototherapeutic window, increased binding affinity toward dsDNA, and similar singlet oxygen quantum yield, therefore advanced DNA photocleavage activity. Both the DNA binding constants and photo nuclease activities of the complexes follow the order 2 (tmp) > 3 (dpq) > 1 (phen), demonstrating the importance of the binding affinity to biomolecules, which improves the bioavailability of reactive oxygen species. Our work opens a new avenue for the development of HB-based PDT agents.     

β-环糊精共聚物及其金属配合物的制备与性能

合成了顺丁烯二酸酐酯化β-环糊精与苯乙烯的共聚物及其金属配合物。 利用红外、紫外、元素分析、差示扫描量热法及热失重分析法对其进行了结构表征和性能测试。 这种含有β-环糊精的共聚物金属配合物作为脲酶抑制剂,对大豆脲酶催化尿素水解的抑制效果显著,其铜金属配合物为4 g/L时,抑制率达96.67%。     

Theoretical study of molecular interaction between tirapazamine enzymatic catalysis metabolites and water

The weakly hydrogen‐bonded complexes, between tirapazamine enzymatic catalysis metabolites and water, have been investigated by density functional theory (DFT), using the B3LYP hybrid functional. The geometries of these complexes have been fully optimized at the B3LYP/6‐31G(d) and B3LYP/6‐311+G(d) levels. The stabilization energies and charge changes of some atoms have been calculated and analyzed. The results indicate that the catalysis metabolites and water can form stable hydrogen‐bonded complexes. Nine complexes are identified. It is important and necessary to add zero‐point vibrational energy (ZPVE) and basis set superposition error (BSSE) corrections for calculating stabilization energy. The results also reveal an important relationship between the relative stabilities of hydrogen‐bonded complexes and the final products of tirapazamine medication. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007     

Shell-anchor-core structures for enhanced stability and catalytic oxygen reduction activity

Density functional theory is used to evaluate activity and stability properties of shell-anchor-core structures. The structures consist of a Pt surface monolayer and a composite core having an anchor bilayer where C atoms in the interstitial sites lock 3d metals in their locations, thus avoiding their surface segregation and posterior dissolution. The modified subsurface geometry induces less strain on the top surface, thus exerting a favorable effect on the surface catalytic activity where the adsorption strength of the oxygenated species becomes more moderate: weaker than on pure Pt(111) but stronger than on a Pt monolayer having a 3d metal subsurface. Here we analyze the effect of changing the nature of the 3d metal in the subsurface anchor bilayer, and we also test the use of a Pd monolayer instead of Pt on the surface. It is found that a subsurface constituted by two layers with an approximate composition of M(2)C (M = Fe, Ni, and Co) provides a barrier for the migration of subsurface core metal atoms to the surface. Consequently, an enhanced resistance against dissolution in parallel to improved oxygen reduction activity is expected, as given by the values of adsorption energies of reaction intermediates, delayed onset of water oxidation, and/or low coverage of oxygenated species at surface oxidation potentials.     

Synthesis,structure and antiproliferative activity of dinuclear ruthenium arene complexes with differently coordinated thiosemicarbazones

A series of di‐nuclear ruthenium arene complexes with TSC ligands ([(η⁶‐p‐cymene)Ru(N¹,S‐TSC)]₂Cl₂, A‐type, 1 and 2 ) and their corresponding analogues ([(η⁶‐p‐cymene)Ru(N²,S‐TSC)]₂Cl₂, B‐type, 3 and 4 ), in which TSCs act as different coordination mode, have been synthesized and structurally characterized by a variety of physical methods. The molecular structures of 1 , 3 and 4 were determined using single‐crystal X‐ray diffraction analysis. The Gibbs free energy of the two examples of the two types of complexes ( 1 and 3 ) and bonding order in their single‐crystals were discussed using density functional theory (DFT) calculations. The compounds were further evaluated for their in vitro antiproliferative activities against several cancerous and HEK‐293 T noncancerous cell lines, and the results indicate that B‐type complexes show stronger cytotoxicity than A‐type complexes. Furthermore, the interactions of the compounds with DNA were investigated by electrophoretic mobility spectrometry studies.     

Template-engineered metal macrocyclic complexes: Synthesis and biological activity

Three new azamacrocylic complexes of divalent transition-metal ions were synthesized by taking Co(II), Ni(II), and Cu(II) metal ions as templates. The macrocyclic ligand (1²Z,5²Z,5⁴E)-1¹,1²,1³,1⁴,1⁵,1⁶,5¹,5²,5³,5⁴,5⁵,5⁶-dodecahydro-2,4,6,8-tetraaza-1 (2,4),5(4,2)-pyrimidine-3,7(1,2)-dibenzenacyclooctaphane-1⁶,5⁶-dione was derived from o-phenylenediamine (OPD) and 2-thiobarbituric acid (TBA). All the complexes were fully characterized through spectroscopic techniques and elemental analyses. The structures of the macrocyclic complexes were determined by IR, UV–vis, ESI-MS, TGA, molar conductance, magnetic moment, and electron spin resonance data. On the basis of the above studies, the complexes may be formulated as [MLX₂], in which L is a macrocyclic ligand and X = CH₃COO⁻. All the macrocyclic complexes were biologically screened to evaluate their antimicrobial efficacy. DNA binding study of two representative complexes was performed by UV–vis titrations.     

Iodine-poly(2-vinylpyridine-co-styrene-co-divinylbenzene) charge transfer complexes with antibacterial activity

In this work, we have developed three different copolymers based on 2-vinylpyridine, styrene and crosslinked with divinylbenzene (10-30 mol%). The copolymers were morphologically and chemically characterized by apparent density, swelling degree, elemental analysis, Fourier transform infrared spectrophotometry and optical microscopy. The formation of iodine complexes with these copolymers was carried out by two different procedures: with solvent, or not. The influence of the copolymers structure on the capacity of anchoring iodine has been investigated. The antibacterial properties of polymeric charge transfer complexes were determined towards 10³-10⁷ cells/mL dilutions from the auxotrophic AB1157 Escherichia coli strain.     

Thermodynamic evaluation of antibacterial activity for inclusion complexes of amoxicillin with cyclodextrins

The antibacterial action of amoxicillin (AMPC) and the inclusion complexes of AMPC with α-, β- and γ-cyclodextrins (α-CD, β-CD and γ-CD, respectively) to Escherichia coli B (E. coli) was evaluated by isothermal titration microcalorimetry and by petri-dish bioassay method. The effects of the compounds on produced heat during the exponential phase of the E. coli growing were measured and the growing rate constants of the cells was calculated from the power-time (p-t) curve before and after the treatment with AMPC. Results from the both methods showed that the antibacterial activity became stronger in the following order: AMPC-βCD > AMPC-γCD ≈ AMPC-αCD > AMPC only.     

Synthesis, structure, and catalytic activity of rhodium complexes with new chiral binaphthyl-based NHC-ligands

Three new chiral NHC-rhodium complexes have been prepared from the reactions between [Rh(COD)Cl]₂, NaOAc, KI, and dibenzimidazolium salts 3, 4 or 5, which are derived from (S)-2,2′-diamino-1,1′-binaphthyl. The steric and electronic effects of the ligand play an important role in the complex formation. For example, treatment of pyridine substituted dibenzimidazolium salts 3 or 4 with 0.5 equiv of [Rh(COD)Cl]₂ in the presence of NaOAc and KI in CH₃CN at 85 °C gives the chiral Rh(III) complexes 6 and 7, respectively. However, under similar reaction conditions, pyridine-N-oxide substituted dibenzimidazolium salt 5 affords a binuclear Rh(I) complex 8. All compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of compounds 4-8 have been further confirmed by X-ray diffraction analyses. Rhodium complexes 6-8 show good catalytic activity for the asymmetric hydrosilylation of acetophenone with moderate ee values.     

Synthesis,characterization, and biological activity of some lanthanide ternary complexes

Five complexes have been synthesized by the reaction of lanthanide(III) nitrate with 2-thenoyltrifluoroacetone (HTTA) and p-hydroxybenzoic acid (L). The complexes have been characterized by elemental analysis, molar conductivity, FT-IR, UV-Vis, ¹H NMR, TG-DTA, XPS, and transmission electron microscope. The general formula of the complexes is Na[Ln(TTA)₃L] (Ln?=?La³⁺,?Ce³⁺,?Nd³⁺,?Eu³⁺,?Er³⁺). The antibacterial activities indicate that all five complexes exhibit antibacterial ability against Escherichia coli and Staphylococcus aureus with broad antimicrobial spectrums. The antitumor activity of the five complexes against K562 tumor cell in vitro is measured using methyl thiazolyl tetrazolium (MTT) colorimetry. The results show that the complexes induce K562 tumor cell apoptosis, and the complexes exhibit inhibitory effect on leukemia K562 cells.     

Synthesis,characterization and study of antibacterial activity of enaminone complexes of zinc and iron

Complexes of enaminones; 4-N,N-diethylamine-pent-3-ene-2-one [HL¹], 4-N,N-di n-propylamine-pent-3-ene-2-one [HL²] and 4-N,N-dicyclohexylamine-pent-3-ene-2-one [HL³] with Fe(II) and Zn(II) ions were prepared by reacting the equimolar ethanolic solutions of the ligands (HL¹, HL² and HL³) with ethanolic metal solutions. The complexes formed, were characterized by infrared, ultraviolet and atomic absorption spectroscopy. Ligands and their metal complexes were tested against Escherichia coli and Staphylococcus aureus bacteria to assess their antibacterial action using disc diffusion method. Ligands were completely inactive against bacteria whereas the complex Zn (HL¹) has significant action on both bacteria, indicating that it has a good potential as bactericide. Other complexes have normal antiseptic character.     

二胍基钛配合物的合成及其催化性能

胍上有三个具有给电子能力的氮原子,胍基负离子[(RN)2C(NR2)]-具有多种共振结构,可以多种方式与金属配位;同时它的空间位阻和电荷效应可以很容易通过氮原子上的取代基进行调控。近年来胍基作为辅助配体在主族和过渡金属配合物的合成中的应用引起了人们的广泛关注,而且发现一些胍基金属配合物显示出了不同于茂基金属配合物的独特的反应性质。但是有关胍基钛配合物的合成与反应性能方面的文献报道还很少。本文报道两个胍基钛的配合物的合成,并对它们的催化聚合活性作了初步研究。     

Syntheses, structures and catalytic activity of copper(II) complexes with hydroxyindanimine ligands

A series of new hydroxyindanimine ligands [ArNCC₂H₃(CH₃)C₆H₂(R)OH] (Ar = 2,6-i-Pr₂C₆H₃, R = H (HL¹), R = Cl (HL²), and R = Me (HL³)) were synthesized and characterized. Reaction of hydroxyindanimine with Cu(OAc)₂ · H₂O results in the formation of the mononuclear bis(hydroxyindaniminato)copper(II) complexes Cu[ArNCC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6-i-Pr₂C₆H₃, R = H (1), R = Cl (2), and R = Me (3)). The complex 2′ was obtained from the chlorobenzene solution of the complex 2, which has the same molecule formula with the complex 2 but it is a polymorph. All copper(II) complexes were characterized by their IR and elemental analyses. In addition, X-ray structure analyses were performed for complexes 1, 2, and 2′. After being activated with methylaluminoxane (MAO), complexes 1-3 can be used as catalysts for the vinyl polymerization of norbornene with moderate catalytic activities. Catalytic activities and the molecular weight of polynorbornene have been investigated for various reaction conditions.