The specific detection of Cu(Ⅱ) using an AIE-active alanine ester

Cu(Ⅱ) detection is important because it plays crucial role in several biological processes and ecological systems.Fluorescent techniques have attracted more and more attention in Cu(Ⅱ) detection.In this report,we contribute a novel strategy to use fluorescence spectroscopy for Cu(Ⅱ) specific detection.The specificity relies on the fact that,of the many metal cations,only Cu(Ⅱ) can catalyze the hydrolyzation of a-amino acid ester.The novelty originates from the unique aggregation-induced emission(AIE) property of the fluorescent label.We designed a model a-amino acid ester(TPE-Ala) constructed with alanine and tetraphenylethene-functionalized methanol(TPE-methanol).In comparison with the precursor TPE-Ala, TPE-methanol has lower solubility and is easy to form aggregates in water,thereby displaying a higher fluorescent response.Thus,the Cu(Ⅱ) catalyzed hydrolyzation can be monitored by recording the fluorescence enhancement and fluorescent detection Cu(Ⅱ) is rationally achieved.     

A novel method for Co(Ⅱ) and Cu(Ⅱ) analysis by capillary electrophoresis with chemiluminescence detection

Based on the fact that some metal ions can catalyze the chemiluminescence(CL)reaction of luminol with K_3Fe(CN)_6,a novel capillary electrophoresis CL method was developed for the determination of Co(Ⅱ)and Cu(Ⅱ).The separation was carried out with a 10 mmol/L sodium acetate solution containing 0.8 mmol/L luminol and 2.0 mmol/Lα-HIBA(adjusted to pH 4.8 by HAc solution).The post-capillary reagent was 2.0 mmol/L K_3Fe(CN)_6 which was adjusted to pH 13.0 by NaOH solution.Under the optimum conditions,the detection limits(S/N=3)for Co(Ⅱ)and Cu(Ⅱ)were 7.5×10~(-11)mol/L and 7.5×10~(-9)mol/L,with the linear range of 7.5×10~(-9)mol/L to 1.0×10~(-6)mol/L and 7.5×10~(-8)mol/L to 5.0×10~(-5)mol/L, respectively.     

CuS–MWCNT based electrochemical sensor for sensitive detection of bisphenol A

The rapid and simple detection of bisphenol A is very important for the safety and reproduction of organisms. Here, a sensitive and reliable electrochemical sensor was established for bisphenol A detection based on the high amplification effect of copper sulfide-multi-walled carbon nanotube (CuS–MWCNT) nanocomposites. The flower-like CuS–MWCNT were successfully synthesized by a simple hydrothermal method accompanied by polyvinylpyrrolidone (PVP). Compared with bare glassy carbon electrode (GCE), CuS–MWCNT modified GCE could amplify the electrochemical signals in about ten times, which was attributed to the synergistic effect of CuS and MWCNT. The MWCNT could increase the specific surface area of electrodes and improve the electrode activity. The integration of CuS could further enhance the electrode conductivity as well as accelerate the electron transfer rate. Raman spectra and transmission electron microscope (TEM) were used to characterize the successful fabrication of CuS–MWCNT nanocomposites and its uniform and monodispersed morphology. Under optimizing conditions, the oxidation currents of bisphenol A via the differential pulse voltammetric (DPV) showed a good linear relationship with its concentration in a wide range of 0.5–100 μM, with a detection limit of 50 nM. This electrochemical sensor of bisphenol A provided a convenient and economical platform with high sensitivity and reproducibility, which had great potential in environmental monitoring.     

Cu(Ⅱ)-catalyzed aerobic oxidative amidation of azoarenes with amides

A method for Cu(Ⅱ)-catalyzed dehydrogenative amidation of azoarene using air as the terminal oxidant was developed. Various amides, such as arylamides, alkylamides, lactams, and imides, are all effective amidation reagents and provide the desired products in moderate to excellent yields. Notably, good yields can also be obtained on a gram-scale with this amidation reaction.In this protocol of azoarene amidation, the catalyst(Cu(OAc)_2) and oxidant(air) are inexpensive and readily available, and the process is highly efficient and atom economical.     

Cu(Ⅰ) and Cu (Ⅱ) helical complexes formed with oligobipyridine ligand

A new asymmetric oligobipyridine ligand, 1-(5'-methyl-2, 2'-bipyridin-5-yl)-2-(6'-methyl-2, 2'-bipyridin-6-yl)ethane (L), in which the bipyridine units are bridged by CH_2CH_2 at 5, 6'-position has been synthesized. The ligand L reacts with Cu(Ⅰ) and Cu(Ⅱ) ions giving double-stranded helical complexes [Cu_2~ⅠL_2] (ClO_4)_2·Et_2O (1) and [Cu_2~ⅡL_2 (OH) (H_2O)][ClO_4]_3(2), respectively. Complexes 1 and 2 were characterized by X-ray diffraction analyses, ES-MS, ESR and cyclic voltammetry, etc. Differing from the oligobipyridine ligands bridged by CH_2CH_2 at 6,6'-or 5,5'-position, the ligand L not only forms a double-stranded helicate with Cu(Ⅰ) ion, but also gives a double-stranded helicate with Cu(Ⅱ) ion. The results show that the linkage mode of the spacer group to the bipyridine units exerts a great impact on the formation of helix.     

Dealing with interference challenge in the electrochemical detection of As(III) —A complexometric masking approach

Copper ion has been reported to be a major interference in the electrochemical detection of arsenic (III) ion in water. Therefore the development of a simple approach to alleviate this interference challenge is important. We present the use of ammonia solution as a masking agent for Cu(II) interference in the square wave anodic stripping voltammetry of As(III) on a gold nanoparticle modified glassy carbon electrode (GCE). AuNPs were electrochemically deposited by cyclic voltammetry on a GCE from a potential range of − 400 mV to 1100 mV for 10 cycles. Square wave anodic stripping voltammetry (SWASV) was used to detect As(III) in water with and without Cu(II) based on the following optimised conditions: pH = 3, deposition potential = − 600 mV, and deposition time = 60 s. Ammonia solution was added to the analyte solution and the effect on mitigating copper interference was studied. The presence of ammonia complexed the Cu(II) ion thereby excluding Cu(II) from interfering with the As(III) signal.     

Real-time detection of individual secondary organic aerosol particle from photooxidation of toluene using aerosol time of flight mass spectrometer

Aromatic hydrocarbons are air pollutants in urban atmosphere and mainly from anthropogenic sources, i.e., emission from automotive exhaust and productive process of industry, and they constitute an important fraction of total volatile organic compounds (VOCs). Photochemical ozone and secondary organic aerosols (SOA) could be formed from the photochemical proc- esses of aromatic hydrocarbons. SOA may impact visibility of air, formation of clouds, change of the climate, and human health serio…     

Why does the electrical conductivity in PEDOT:PSS decrease with PSS content? A study combining thermoelectric measurements with impedance spectroscopy

We have investigated the electrical transport properties of poly(3,4‐ethylenedioxythiophen)/poly(4‐styrene‐sulfonate) (PEDOT:PSS) with PEDOT‐to‐PSS ratios from 1:1 to 1:30. By combining impedance spectroscopy with thermoelectric measurements, we are able to independently determine the variation of electrical conductivity and charge carrier density with PSS content. We find the charge carrier density to be independent of the PSS content. Using a generalized effective media theory, we show that the electrical conductivity in PEDOT:PSS can be understood as percolation between sites of highly conducting PEDOT:PSS complexes with a conductivity of 2.3 (Ωcm)^?1 in a matrix of excess PSS with a low conductivity of 10^?3 (Ω cm)^?1. In addition to the transport properties, the thermoelectric power factors and Seebeck coefficients have been determined. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Magnetic nanomaterial–based electrochemical biosensors for the detection of diverse circulating cancer biomarkers

Electrochemical biosensors are highly compatible with modern advancements in magnetic nanomaterials. In particular, the versatile nature of magnetic nanomaterials as a universal platform for selective isolation of diverse forms of cancer biomarkers in body circulation, is highly synergistic with electrochemical biosensors for elevating biosensing performance to unprecedented levels. Such diverse circulating target biomolecules include cell surface proteins of circulating tumor cells and extracellular vesicles (EVs), as well as circulating tumor nucleic acids (i.e. ctDNA/ctRNA). This focussed review serves to discuss the latest work in the fields of magnetic nanomaterials and electrochemistry to tackle existing analysis challenges of diverse circulating biomarkers in cancer.     

Cerium oxide nanofiber–based electrochemical immunosensor for detection of sepsis in biological fluid

Sepsis causes life-threatening complications with the highest burden of death and medical expenses in hospitals worldwide. Despite the progression of targeted therapies for sepsis, the challenge of early diagnosis of sepsis-related biomarkers remains. The analysis of the TNF-α and sTREM-1 in biological fluids provides essential information for effective treatments. In this work, we report developing an electrochemical immunosensor for the rapid detection of TNF-α and sTREM-1 proteins in human plasma samples. First, using the electrospinning process, cerium oxide nanofibers were synthesized. Subsequently, the antibodies corresponding to the targeted proteins are immobilized onto the surface-functionalized working electrodes using NHS/EDC chemistry. The proposed immunosensor’s performance in a biological fluid was assessed using an analytical electrochemistry approach. The limit of detection for the electrochemical immunosensors was 0.51 and 0.41 pg/mL for TNF-α and sTREM-1, respectively, with high selectivity and sensitivity for the use as a point of care device.

     

An electrochemical signal switch–based (on–off) aptasensor for sensitive detection of insulin on gold-deposited screen-printed electrodes

Journal of Solid State Electrochemistry - Insulin hormone is of great importance for many diseases, especially for diabetes management. Therefore, different detection strategies have been used for...     

Ratiometric electrochemical detection of Pd•••π interactions: application towards electrochemical molecular logic gates

Abstract

The widespread and large scale use of platinum group metals, especially palladium, in a wide variety of industrial applications has seen their levels in wastewater streams, roadside dust and even pharmaceuticals significantly rise over recent years. Due to the possible environmental damage and potential health risk this may cause, there is now substantial demand for inexpensive, efficient and robust methods for the detection of palladium. Based upon self-immolative linker technologies, we have designed and synthesised a number of allyl ether-functionalised electrochemical probes to determine the optimum probe structure required to deliver a ratiometric electrochemical detection method capable of achieving a limit of detection of <1 mg/mL within 20 min through the use of disposable screen-printed carbon electrodes. Combined with an enzymatic assay, this method was then used to achieve a proof-of-principle ratiometric electrochemical molecular logic gate.     

Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by Cu(Ⅱ)-imine complex

A series of new ligands L₁-L₇ were readily prepared in one step.Friedel-Crafts alkylation of indoles with nitroalkenes catalyzed by a novel Cu（Ⅱ）-L complex has been developed.The remarkable advantages of this reaction are mild reaction conditions,simple workup procedure,high yields of products and the use of ethanol as a green solvent.     

An electrochemical biosensor based on DNA “nano-bridge” for amplified detection of exosomal microRNAs

Exosomal miRNAs, as potential biomarkers in liquid biopsy for cancer early diagnosis, have aroused widespread concern. Herein, an electrochemical biosensor based on DNA “nano-bridge” was designed and applied to detect exosomal microRNA-21 (miR-21) derived from breast cancer cells. In brief, the target miR-21 can specifically open the hairpin probe 1(HP1) labeled on the gold electrode (GE) surface through strand displacement reaction. Thus the exposed loop region of HP1 can act as an initiator sequence to activate the hybridization chain reaction (HCR) between two kinetically trapped hairpin probes: HP2 immobilized on the GE surface and biotin labeled HP3 in solution. Cascade HCR leads to the formation of DNA “nano-bridge” tethered to the GE surface with a great deal of “piers”. Upon addition of avidin-modified horseradish peroxidase (HRP), numerous HRP were bound to the formed “nano-bridge” through biotin-avidin interaction to arouse tremendous current signal. In theory, only a single miR-21 is able to trigger the continuous HCR between HP2 and HP3 until all of the HP2 are exhausted. Therefore the proposed biosensor achieved ultrahigh sensitivity toward miR-21 with the detection limit down to 168 amol/L, as well as little cross-hybridization even at the single-base-mismatched level. Successful attempts were also made in the detection of exosomal miR-21 obtained from the MCF-7 of breast cancer cell line. To our knowledge, this is the first attempt to built horizontal DNA nano-structure on the electrode surface for exosomal miRNAs detection. In a word, the high sensitivity, selectivity, low cost make the proposed method hold great potential application for early point-of-care (POC) diagnostics of cancer.     

Synthesis and Properties of u-Oxamido Heterobinuclear Cu(Ⅱ)-Co(Ⅱ) Complexes

Three heterobinuclear complexes were synthesized, namely [Cu (oxpn) Co (L)2] (ClO4)2·xH2O(L= 2,2'-bipyridyl(bpy), 1,10-phenanthroline(phen) , and 5-nitro-1, 10-phenanthroline (NO2-phen)), where oxpn represents N, N'-bis(3-aminopropyl) oxam-ido. Based on 1R, elemental analysis, conductivity measurement and electronic spectra, these complexes were characterized by an extended oxamido-bridged structure with Cu(Ⅱ) in a planar environment and Co(Ⅱ) in a octahedral environment. The symmetry of the cation is very close to C2v.The complexes were also characterized with variable temperature (4~300K) magnetic susceptibility, and the data were fit for the susceptibility equation derived from spin Hamilton, H= -2JS1.S2-DSx12 by least square strategy. The exchange integral, J, was found to be -22.36 cm-1 (for bpy);-15.45 cm-1 (for phen); -19. 10cm-1(for NO2-phen), indicating that there is a weak antiferromagnetic spin-exchange interaction between the metal ions.     

Crystal Structures of Cu(Ⅰ) and Cu(Ⅱ) Complexes of Tris(N-n-propylbenzimidazol-2-ylmethyl)amine

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Cu(Ⅱ)-VO(Ⅱ),Cu(Ⅱ)-Cr(Ⅲ)和Cu(Ⅱ)-Fe(Ⅲ)异双核配合物的合成及表征

合成了三种二 ( 3 羧基水杨醛叉 )缩丙撑二胺 (TS)的Cu(Ⅱ ) VO(Ⅱ )、Cu(Ⅱ ) Cr(Ⅲ )、Cu(Ⅱ ) Fe(Ⅲ )异双核配合物 ,并用元素分析、摩尔电导、IR光谱、UV光谱室温磁矩对配合物的组成和结构进行了表征。磁性研究表明 ,在Cu(Ⅱ ) Fe(Ⅲ )离子间的磁相互作用是反铁磁性的 ,而Cu(Ⅱ ) VO(Ⅱ )、Cu(Ⅱ ) Cr(Ⅲ )离子间是铁磁性相互作用。     

Synthesis and Magnetic Studies of Oxamido-Bridged Cu(Ⅱ)-Fe(Ⅱ) Heterobinuclear Complexes

~The~andmagneti~Of~~areatoPicthahasndchinndinndnd.bondinthewiin-wtofbinudearCU(n)-Fe(u)-,chewedwiththe~alleq-nettrioftwnew~-,[CU(oxa)Fe(L)21sa(Lbo1,1o-~(Phen)nd5-nithe1'1o-~(NQ-Phen)),whereOxaisN,N'-bis(2-amhathy).edfor.-Synboor(1)ToCh(oxae)2(94.2mp'o.4ed)theindri(5nd)wasbo-lyadtalaedboofso.Wio(111.2mp,o.4nuno)inmeto(1ond)ndaboofPhen(144-2mp,o.8mrnO)inrne~(1OrnL)underN2atrmpe.theedfor2hthegreddebm~thuSfo~wereforoff,washededtimeswithrne~anddiethyletheranddriedoverP2QUnderededpe.ha:C,…     

Two Cu(Ⅱ) Complexes with Hydrolyzed Nicotinamide Ligand: Crystal Structures and Bioactivities

Two Cu(Ⅱ) complexes of [Cu(2,6-DPC)(Hnta)(H_2O)]·H_2O(2,6-DPC = 2,6-pyridinedicarboxylic-carboxylate, Hnta = nicotinic acid) and [Cu_2(2,4-D)_4(Hnta)_2](2,4-D = 2,4-dichlorophenoxyacetic-carboxylate) were synthesized and successfully obtained as single crystals in this paper. The supramolecular structures of the complexes from zero to three dimensions and the weak intermolecular force in the crystal were analyzed. The single-crystal structures of the complexes were further analyzed by Hirshfeld surface analysis. The competition capacity of the complexes about calf thymus DNA(ct-DNA) was also analyzed by fluorescence spectroscopy. The ability of complexes to cleave the plasmid DNA(pBR322-DNA) was determined by gel electrophoresis assay. And at last, the complexes' cytotoxic activities were reviewed for four kinds of cancer cell lines(HeLa, MCF-7, HepG, SKOV-3), showing that the coordination polymer has anti-tumor activity and cytotoxicity.