过渡金属硫簇的几种簇骼转化反应

报道了过渡金属硫簇化合物的几种簇骼转化反应，即三核链状簇的转化；双核配合物的组合；Ｍｏ２Ｆｅ７Ｓ８和Ｍｏ２Ｆｅ６Ｓ８两种双立方烷的关联；Ｆｅ４Ｓ４立方烷簇向篮状簇的转化；簇降解以及簇骼原子置换反应等。探讨了配体及氧化还原条件对簇骼转化反应的影响。     

Transitional Metal/Chalcogen Dependant Interactions of Hairpin DNA with Transition Metal Dichalcogenides,MX2

Owing to the attractive properties that transition metal dichalcogenides (TMDs) display, they have found recent application in the fabrication of biosensing devices. These devices involve the immobilization of a recognition element such as DNA onto the surface of TMDs. Therefore, it is imperative to examine the interactions between TMDs and DNA. Herein, we explore the effect of different transition metals (Mo and W) and chalcogens (S and Se) on the interactions between hairpin DNA and TMDs of both bulk and t‐BuLi exfoliated forms. We discovered that the interactions are strongly dependent on the metal/chalcogen composition in TMDs.     

Synthesis,characterization and biological activities of two novel orthopalladated complexes: Interactions with DNA and bovine serum albumin,antitumour activity and molecular docking studies

[Pd(L₁)(C,N)]CF₃SO₃ and [Pd(L₂)(C,N)]CF₃SO₃ (L₁ = 2,2′ ‐bipyridine, L₂ = 1,10‐phenanthroline and C,N = benzylamine) novel orthopalladated complexes have been synthesized and characterized using various techniques. The binding of the complexes with native calf thymus DNA (CT‐DNA) was monitored using UV–visible absorption spectrophotometry, fluorescence spectroscopy and thermal denaturation studies. Our results indicate that these complexes can strongly bind to CT‐DNA via partial intercalative mode. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the complexes shows that the fluorescence quenching mechanism of BSA is a static process. The results of site‐competitive replacement experiments with specific site markers clearly indicate that the complexes bind to site I of BSA. Notably, the complexes exhibit significant in vitro cytotoxicity against two human cancer cell lines (Jurkat and MCF‐7) with IC₅₀ values varying from 37 to 53 μM. Finally, a molecular docking experiment effectively proves the binding of the Pd(II) complexes to DNA and BSA.     

Rare-Earth Metal Complexes of the Antibacterial Drug Oxolinic Acid: Synthesis,Characterization, DNA/Protein Binding and Cytotoxicity Studies

“Drug repositioning” is a current trend which proved useful in the search for new applications for existing, failed, no longer in use or abandoned drugs, particularly when addressing issues such as bacterial or cancer cells resistance to current therapeutic approaches. In this context, six new complexes of the first-generation quinolone oxolinic acid with rare-earth metal cations (Y³⁺, La³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺) have been synthesized and characterized. The experimental data suggest that the quinolone acts as a bidentate ligand, binding to the metal ion via the keto and carboxylate oxygen atoms; these findings are supported by DFT (density functional theory) calculations for the Sm³⁺ complex. The cytotoxic activity of the complexes, as well as the ligand, has been studied on MDA-MB 231 (human breast adenocarcinoma), LoVo (human colon adenocarcinoma) and HUVEC (normal human umbilical vein endothelial cells) cell lines. UV-Vis spectroscopy and competitive binding studies show that the complexes display binding affinities (K_b) towards double stranded DNA in the range of 9.33 × 10⁴ − 10.72 × 10⁵. Major and minor groove-binding most likely play a significant role in the interactions of the complexes with DNA. Moreover, the complexes bind human serum albumin more avidly than apo-transferrin.     

Oxovanadium(IV) and ruthenium(II) carbonyl complexes of ONS‐donor ligands derived from dehydroacetic acid and dithiocarbazate: Synthesis,characterization, antioxidant activity,DNA binding and in vitro cytotoxicity

A series of new complexes of oxovanadium(IV) [VO(L)(B)] and ruthenium(II) [Ru(CO)(PPh₃)₂(L)] ( 1.1- 1.3,  2.1–2.3 ) (H₂L = dehydroacetic acid Schiff base of S‐methyldithiocarbazate, H₂smdha ( 1 ) or S‐benzyldithiocarbazate, H₂sbdha ( 2 ); B = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen)) have been synthesized. The structure of these complexes was authenticated using elemental analyses and spectroscopic techniques, and their magnetic properties and electrochemical behaviour were studied. The molecular structures of oxovanadium(IV) complexes [VO(smdha)(bpy)]?CH₂Cl₂ ( 1.1 ) and [VO(sbdha)(phen)]?2H₂O ( 2.2 ) were confirmed using single‐crystal X‐ray crystallography. Analytical data showed that the ligands 1 and 2 are chelated to the metal centres in a bi‐negative tridentate fashion through azomethine N, thiol S and deprotonated hydroxyl group. The antioxidant activity of the synthesized compounds was tested against 2,2‐diphenyl‐1‐picrylhydrazyl) radical, which showed that the complexes demonstrate a better scavenging activity than their corresponding ligands. The cupric ion reducing antioxidant capacity method was also employed and the total equivalent antioxidant capacity values were found to be higher for the oxovandium(IV) complexes. DNA binding affinity of the compounds was determined using UV–visible and fluorescence spectra, revealing an intercalation binding mode. Higher cytotoxicity for the complexes compared to their ligands was found against human liver hepatocellular carcinoma (HepG2) and breast adenocarcinoma (MCF7) cell lines using MTT assay.     

桑色素及其配合物与DNA作用的比较

采用光度法、粘度法和电化学方法考察了桑色素及其配合物和DNA的作用.并对桑色素合铜(Ⅱ)、桑色素合锌(Ⅱ)、桑色素合钴(Ⅱ)、桑色素与DNA作用的方式进行了比较.Cu(Ⅱ), Zn(Ⅱ), Co(Ⅱ)桑色素配合物与DNA作用时的荧光光谱性质类似,不同于配体.钴(Ⅱ)配合物的电化学行为与铜(Ⅱ)配合物相似,不同于锌(Ⅱ)配合物.三种配合物的存在,都可引起DNA的粘度增加.但钴(Ⅱ)配合物对EB-DNA复合物的荧光光谱影响很小,而铜(Ⅱ)、锌(Ⅱ)配合物对EB-DNA复合物的荧光光谱影响较大.实验结果表明,与DNA之间的作用,钴(Ⅱ)配合物弱于铜(Ⅱ)、锌(Ⅱ)配合物.这可能是钴(Ⅱ)配合物的抗肿瘤活性低于与DNA嵌入结合的铜(Ⅱ)、锌(Ⅱ)配合物的原因之一.     

Physical and Chemical Properties of Large Metal and Semiconductor Clusters in View of Future Applications

Metal and semiconductor clusters in the nanometer size regime exhibit quantum size behavior which is demonstrated by means of scanning tunneling spectroscopy and scanning capacitance microscopy on single clusters. Cluster monolayers can be prepared by self-assembly processes on modified surfaces of substrates. Clusters in the channels of nanoporous alumina are promising candidates not only for a novel kind of cluster arrangement for future electronic applications but also for the easy generation of light emitting diodes.     

Solid State Electrochemical Oxidation of Some Bisphosphoramidates in Aqueous Media and their Applications in DNA Sensing

Bisphosphoramidates are known as anticancer, antibacterial, antiviral drugs and enzyme inhibitory agents. These compounds are electroactive and insoluble in aqueous media. Hence, a comprehensive study about the electrochemical properties of them seems very interesting. The oxidative behaviors of some bisphosphoramidates were studied in buffer solution over a wide pH range by cyclic voltammetry and differential pulse voltammetry using spiked carbon paste electrodes. The interaction of these compounds with calf thymus DNA (CT‐DNA) showed the ability of these compounds as DNA sensing. The decrease in the anodic peaks of bisphosphoramidates in the presence of DNA was used for the DNA monitoring.     

Antibody–Drug Conjugates: An Emerging Concept in Cancer Therapy

Traditional cancer chemotherapy is often accompanied by systemic toxicity to the patient. Monoclonal antibodies against antigens on cancer cells offer an alternative tumor‐selective treatment approach. However, most monoclonal antibodies are not sufficiently potent to be therapeutically active on their own. Antibody–drug conjugates (ADCs) use antibodies to deliver a potent cytotoxic compound selectively to tumor cells, thus improving the therapeutic index of chemotherapeutic agents. The recent approval of two ADCs, brentuximab vedotin and ado‐trastuzumab emtansine, for cancer treatment has spurred tremendous research interest in this field. This Review touches upon the early efforts in the field, and describes how the lessons learned from the first‐generation ADCs have led to improvements in every aspect of this technology, i.e., the antibody, the cytotoxic compound, and the linker connecting them, leading to the current successes. The design of ADCs currently in clinical development, and results from mechanistic studies and preclinical and clinical evaluation are discussed. Emerging technologies that seek to further advance this exciting area of research are also discussed.     

Phosphoester binding,DNA binding,DNA cleavage and in vitro cytotoxicity studies of simple heteroleptic copper(II) complexes with bidentate ligands

Abstract

Two mononuclear heteroleptic copper complexes, [Cu(±trans-dach)(bpy)](ClO₄)₂ 1a and [Cu(±trans-dach)(phen)](ClO₄)₂ 2a [dach?=?1,2-diaminocyclohexane, bpy?=?2,2′-bipyridine and phen?=?1,10-phenanthroline], were synthesized and analyzed by CHN analysis, electronic absorption, FT-IR spectroscopy, EPR, and SXRD. The molecular structures of 1a and 2a showed octahedral geometry around Cu(II). Both complexes interacted with phosphoesters and DNA. Their binding affinities with diphenylphosphate, di n-butylphosphate, trimethylphosphate, and triphenylphosphate were studied by UV–vis spectroscopy. For understanding the stereochemical role of dach ligand toward DNA interaction, enantiopure DACH complexes [Cu(R,R-trans-dach(bpy)](ClO₄)₂ 1b, [Cu(S,S-trans-dach)(bpy)](ClO₄)₂ 1c, [Cu(cis-dach)(bpy)](ClO₄)₂ 1d, [Cu(R,R-trans-dach)(phen)](ClO₄)₂ 2b, [Cu(S,S-trans-dach)(phen)](ClO₄)₂ 2c, and [Cu(cis-dach)(phen)](ClO₄)₂ 2d were synthesized and analyzed. All complexes interacted with calf thymus-DNA (CT-DNA) as studied by UV–vis spectroscopy. The nature of binding to CT-DNA was groove/electrostatic as supported by circular dichroism, cyclic voltammetry, and docking studies. Complexes were able to cleave plasmid DNA at 12.5 µM (1a–d) and 6 µM (2a–d), where 2d showed 64% Form II and 36% Form III. The in vitro cytotoxic studies of two different cancer cell lines showed inhibition with low IC₅₀ value in comparison to reference control (cisplatin). These complexes are efficient in inducing apoptosis in cancer cells, making them viable for potent anticancer activity.     

Water-Soluble Rhenium Clusters with Triazoles: The Effect of Chemical Structure on Cellular Internalization and the DNA Binding of the Complexes

Here we explore the effect of the nature of organic ligands in rhenium cluster complexes [Re₆Q₈L₆]⁴⁻ (where Q=S or Se, and L=benzotriazole, 1,2,3-triazole or 1,2,4-triazole) on the biological properties of the complexes, in particular on the cellular toxicity, cellular internalization and localization. Specifically, the study describes the synthesis and detailed characterization of the structure, luminescence and electrochemical properties of the four new Re₆ clusters with 1,2,3- and 1,2,4-triazoles. Biological assays of these complexes are also discussed in addition to those with benzotriazole using cervical cancer (HeLa) and immortalized human fibroblasts (CRL-4025) as model cell lines. Our study demonstrates that the presence of hydrophobic and π-bonding rich units such as the benzene ring in benzotriazole significantly enhances cellular internalization of rhenium clusters. These ligands facilitate binding of the clusters to DNA, which results in increased cytotoxicity of the complexes.     

Electron－rich Polynuclear Transition Metal Clusters：Ⅰ． The Clusters with Chalcogen Bridges and Phosphine Ligands

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Ag2 and Ag3 Clusters: Synthesis,Characterization, and Interaction with DNA

Subnanometric samples, containing exclusively Ag₂ and Ag₃ clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag₃ clusters interact with DNA through intercalation, inducing significant structural distortion to the DNA. The lifetime of Ag₃ clusters in the intercalated position is two to three orders of magnitude longer than for classical organic intercalators, such as ethidium bromide or proflavine.     

Interaction of Metal Complexes with G‐Quadruplex DNA

Guanine‐rich sequences of DNA can assemble into tetrastranded structures known as G‐quadruplexes. It has been suggested that these secondary DNA structures could be involved in the regulation of several key biological processes. In the human genome, guanine‐rich sequences with the potential to form G‐quadruplexes exist in the telomere as well as in promoter regions of certain oncogenes. The identification of these sequences as novel targets for the development of anticancer drugs has sparked great interest in the design of molecules that can interact with quadruplex DNA. While most reported quadruplex DNA binders are based on purely organic templates, numerous metal complexes have more recently been shown to interact effectively with this DNA secondary structure. This Review provides an overview of the important roles that metal complexes can play as quadruplex DNA binding molecules, highlighting the unique properties metals can confer to these molecules.     

色胺修饰竹红菌素及其稀土离子配位聚合物与DNA相互作用研究

利用紫外-可见吸收光谱、荧光光谱、圆二色谱(CD)等方法研究了色胺修饰竹红菌素(DTrpHA)及其稀土离子配位聚合物(Y³⁺-DTrpHA, La³⁺-DTrpHA)与小牛胸腺DNA (CT DNA)和G-四链体22AG的相互作用.结果表明, DTrpHA及其配位聚合物中的色胺基团和竹红菌素基团均参与和双链CT DNA的作用,作用方式主要为沟槽作用.与G-四链体DNA作用后, DTrpHA及其配位聚合物中的色胺基团均具有较大的减色效应(> 45%)和峰位红移(≥ 4 nm),说明色胺基团与G-四链体采用外部堆积作用方式结合;而竹红菌素基团的减色效应相对较小且无明显峰位变化,表明竹红菌素基团采用非特异性作用方式与G-四链体的环区碱基或糖-磷酸骨架结合. G-四链体22AG的构象主要为分子内反平行结构,加入DTrpHA及其配位聚合物对G-四链体22AG的构象影响较小. Y³⁺-DTrpHA比DTrpHA和La³⁺-DTrpHA与G-四链体具有更强的相互作用. Y³⁺-DTrpHA使得CT DNA的熔解温度(T_m)上升了仅1.9 ℃,而使G-四链体的熔解温度上升了13.1 ℃.荧光嵌插剂置换实验 (FID)结果表明, Y³⁺-DTrpHA对G-四链体具有良好亲和性,具有较小的^G4DC₅₀值(使噻唑橙/G-四链体体系荧光下降50%所需配体或配合物的浓度)和较高的G-四链体选择性.     

Initial DNA Interactions of the Binuclear Threading Intercalator Λ,Λ‐[μ‐bidppz(bipy)4Ru2]4+: An NMR Study with [d(CGCGAATTCGCG)]2

Binuclear polypyridine ruthenium compounds have been shown to slowly intercalate into DNA, following a fast initial binding on the DNA surface. For these compounds, intercalation requires threading of a bulky substituent, containing one Ru^II, through the DNA base‐pair stack, and the accompanying DNA duplex distortions are much more severe than with intercalation of mononuclear compounds. Structural understanding of the process of intercalation may greatly gain from a characterisation of the initial interactions between binuclear Ru^II compounds and DNA. We report a structural NMR study on the binuclear Ru^II intercalator Λ,Λ‐B (Λ,Λ‐[μ‐bidppz(bipy)₄Ru₂]⁴⁺; bidppz=11,11′‐bis(dipyrido[3,2‐a:2′,3′‐c]phenazinyl, bipy = 2,2′‐bipyridine) mixed with the palindromic DNA [d(CGCGAATTCGCG)]₂. Threading of Λ,Λ‐B depends on the presence and length of AT stretches in the DNA. Therefore, the latter was selected to promote initial binding, but due to the short stretch of AT base pairs, final intercalation is prevented. Structural calculations provide a model for the interaction: Λ,Λ‐B is trapped in a well‐defined surface‐bound state consisting of an eccentric minor‐groove binding. Most of the interaction enthalpy originates from electrostatic and van der Waals contacts, whereas intermolecular hydrogen bonds may help to define a unique position of Λ,Λ‐B. Molecular dynamics simulations show that this minor‐groove binding mode is stable on a nanosecond scale. To the best of our knowledge, this is the first structural study by NMR spectroscopy on a binuclear Ru compound bound to DNA. In the calculated structure, one of the positively charged Ru²⁺ moieties is near the central AATT region; this is favourable in view of potential intercalation as observed by optical methods for DNA with longer AT stretches. Circular dichroism (CD) spectroscopy suggests that a similar binding geometry is formed in mixtures of Λ,Λ‐B with natural calf thymus DNA. The present minor‐groove binding mode is proposed to represent the initial surface interactions of binuclear Ru^II compounds prior to intercalation into AT‐rich DNA.     

Structures of Medium‐Sized Ruthenium Clusters: The Octahedral Motif

We describe the first direct structural characterization of medium‐sized ruthenium clusters (Ru₁₉^?, Ru₂₈^?, Ru₃₈^?, and Ru₄₄^?) by using a combination of trapped ion electron diffraction and density functional theory. We find close‐packed structures based on octahedral geometries: Ru₁₉^? and Ru₄₄^? are closed‐shell octahedra whereas Ru₂₈^? is a double octahedron. In the case of Ru₃₈^?, instead of a truncated octahedron we obtain evidence for lower symmetry structures containing a reentrant surface.     

Drug Delivery Applications of Coaxial Electrospun Nanofibres in Cancer Therapy

Cancer is one of the most serious health problems and the second leading cause of death worldwide, and with an ageing and growing population, problems related to cancer will continue. In the battle against cancer, many therapies and anticancer drugs have been developed. Chemotherapy and relevant drugs are widely used in clinical practice; however, their applications are always accompanied by severe side effects. In recent years, the drug delivery system has been improved by nanotechnology to reduce the adverse effects of the delivered drugs. Among the different candidates, core–sheath nanofibres prepared by coaxial electrospinning are outstanding due to their unique properties, including their large surface area, high encapsulation efficiency, good mechanical property, multidrug loading capacity, and ability to govern drug release kinetics. Therefore, encapsulating drugs in coaxial electrospun nanofibres is a desirable method for controlled and sustained drug release. This review summarises the drug delivery applications of coaxial electrospun nanofibres with different structures and drugs for various cancer treatments.