Chemistry Commons^™

Quantification Of Copper Content With Laser Induced Breakdown Spectroscopy As A Potential Indicator Of Offal Adulteration In Beef, Maria Piedad Casado-Gavalda, Yash Dixit, David Geulen, Raquel Cama-Moncunill, Xavier Cama-Moncunill, Maria Markiewicz-Keszycka, Patrick J. Cullen, Carl Sullivan

Articles

Laser induced breakdown spectroscopy (LIBS) is an emerging technique in the field of food analysis which provides various advantages such as minimal sample preparation, chemical free, rapid detection, provision of spatial information and portability. In this study, LIBS was employed for quantitative analysis of copper content in minced beef samples spiked with beef liver over three independent batches. Copper content was determined with graphite furnace atomic absorption spectroscopy (GFAAS) in order to obtain reference values for modelling. Partial least square regression (PLSR) was performed to build a calibration and validation model. A calibration model with a high Rcv2 of 0.85 …

Copper Salt-Catalyzed Formation Of A Novel Series Of Triazole-Spirodienone Conjugates With Potent Anticancer Activity., L. Gu, P. Wang, Qiu Zhong, Y. Deng, J. Xie, F. Liu, F. Xiao, Shilong Zheng, Y. Chen, Guangdi Wang, L. He

Faculty and Staff Publications

Copper salt-catalyzed oxidative amination resulted in the formation of a novel series of triazole-spirodienone conjugates, 4-triazolyl-1-oxa-4-azaspiro[4,5]deca-6,9-dien-3,8-diones and 4-triazolyl-1-oxa-4-azaspiro[4,5]deca-6,9-dien-8-ones. A single crystal of compound 1p among them was grown and analyzed by X-ray crystallography. These compounds were evaluated for their antiproliferative activities against MDA-MB-231, HeLa, A549 and MCF-7 cell lines. Most of them showed moderate to high anticancer potency in the four cancer cell lines. The discovery of the triazole-spirodienone conjugates as cytotoxic agents against cancer cells may open up a new field in which these novel small molecules could be further explored as promising anticancer agents.

Investigation On Laser Induced Deposition Of Cu-Based Materials At [Bmim]Bf4/Pt Electrode Interface, Min-Min Xu, Jin-Hua Mei, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

By controlling the negative potential, Cu-based materials were deposited at the [BMIm]BF₄/Pt electrode interface under the laser irradiation. The effects of laser power and irradiation time on the yield of deposition products were studied by using different laser powers and different irradiation time. The product yield could be directly determined by the size of deposition point through the observation from the optical microscope. Further mechanism study combined with the formula deduced that the thermal effect of the laser could make the electrode surface temperature rise 110 degrees, which can promote the occurrence of electrodeposition. By SEM characterization, the …

Dendrimer Modified Silica Nanoparticles As Fluorescent Chemosensors For The Detection Of Copper And Cyanide Ions, Alicia Luhrs

Master's Theses

A series of silica nanoparticle-based fluorescent chemosensors were synthesized for the sensitive and selective detection of Cu²⁺ ions in aqueous solution and subsequent CN^- ion detection. Silica nanoparticles (SNP) were modified with branching polyamidoamine (PAMAM) dendrimers, which function as selective turn-off Cu²⁺ ion chelators and platforms for the attachment of rhodamine isothiocyanate (RITC) or fluorescein isothiocyanate (FITC) fluorescent dyes. In the presence of Cu²⁺ ions, the emission of the fluorescent dye is quenched by Forster resonance energy transfer (FRET) and is dependent upon dendrimer generation, pH, fluorescent dye, and surface charge. The quenching effectiveness was analyzed …

Highly Fluorinated, Coinage Metal Complexes Of Tris(Pyrazolyl)Borates With Additional Electron Withdrawing Groups And Pyrazolate Π-Stackings With Arenes, Naleen Bandupriya Jayaratna

Chemistry & Biochemistry Dissertations - Archive

Tris(pyrazolyl)borates are very popular ligands in inorganic chemistry, bioinorganic chemistry, and organometallic chemistry due to their attractive properties. It is possible to extensively modify the steric and electronic properties of these ligands by changing the pyrazolyl substituent groups. Taking into account the importance and current interest of fluorinated tris(pyrazolyl)borates and weakly coordinating anions in general, three new tris(pyrazolyl)borates, [HB(4-Cl-3,5-(CF₃)₂Pz)₃]-, [HB(3,4,5-(CF₃)3Pz)₃] and [HB(4-(NO₂)-3,5-(CF3)₂Pz)₃]- have been developed (Pz = pyrazolyl). Silver alkene adducts of the ligands have been isolated to evaluate the electronic properties of the ligands and to study their catalytic properties. These adducts found to be the most electron deficient …

Removal Of Cu (Ii) And Pb (Ii) From Aqueous Solution Using Engineered Iron Oxide Nanoparticles, Carlos Tamez, Rebecca Hernandez, Jason Parsons

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Nano-sized Fe3O4 and Fe2O3 were synthesized using a precipitation method. The nanomaterials were tested as adsorbents for the removal of both Cu2+ and Pb2+ ions. The nanomaterials were characterized using X-ray powder diffraction to determine both the phase and the average grain size of the synthesized nanomaterials. Batch pH studies were performed to determine the optimum binding pH for both the Cu2+ and Pb2+ to the synthesized nanomaterials. The optimum binding was observed to occur at pH 4 and above. Time dependency studies for Cu2+ and Pb2+ showed the binding occurred within the first five minutes of contact and remained …

Novel Approaches For Assessment Of Copper Toxicity: Fast Scan Cyclic Voltammetry And Optical Bioassays, Annette R. Tremonti

Wayne State University Dissertations

Anthropogenic activities negatively impact fresh water ecosystems through toxic contaminants that are released into the environment. Copper (Cu) is a water contaminant that is fundamentally persistent once introduced into the environment that has the potential for bioaccumulation. Although Cu toxicity has been studied for decades, there is still a continuing problem with new sources and pathways. New approaches are needed to understand distribution and transport of Cu and its potential for complex biological impacts beyond the simple assessment of lethality. Several novel approaches were used in this research project to advance our understanding of Cu toxicity, including fast scan cyclic …

A Novel, Ultra-Fast Electrochemical Tool To Study Speciation Of Trace Metals In Aqueous Solution, Pavithra Pathirathna

Wayne State University Dissertations

Trace metals play important roles in biological and ecological systems. In biology, trace metals act as catalytic or structural cofactors and regulate biochemical processes. In the environment, natural and anthropogenic sources of trace metals mobilized into natural waters where they can create harmful and persistent pollution. Trace metal chemistry in physiological and environmental systems can fluctuate rapidly which makes it difficult to clearly define trace metals’ roles in these systems with traditional analytical methods. Furthermore, these systems are often chemically harsh and physically delicate (e.g. the brain), factors that add to the challenge of analysis in real systems. Fast scan …

Electronic Structure And Stability Of Ligated Superatoms And Bimetallic Clusters, William H. Blades

Theses and Dissertations

Quantum confinement in small metal clusters leads to a bunching of states into electronic shells reminiscent of shells in atoms. The addition of ligands can tune the valence electron count and electron distribution in metal clusters. A combined experimental and theoretical study of the reactivity of methanol with Al_nI_m⁻ clusters reveals that ligands can enhance the stability of clusters. In some cases the electronegative ligand may perturb the charge density of the metallic core generating active sites that can lead to the etching of the cluster. Also, an investigation is conducted to understand how the bonding …

Analytical Capabilities Of Two-Phase Hollow-Fiber Liquid Phase Microextraction For Trace Multielement Determination In Aqueous Samples By Means Of Portable Total Reflection X-Ray Instrumentation, Eva Margui, Manuela Hidalgo

Turkish Journal of Chemistry

Liquid phase microextraction (LPME) procedures have been widely used in combination with atomic and emission spectroscopic techniques for the isolation and preconcentration of trace elements. However, its application in combination with total reflection X-ray spectrometry (TXRF) is still scarce. In this paper, we evaluate the possibilities and drawbacks of a two-phase hollow fiber LPME procedure in combination with TXRF for the simultaneous determination of trace amounts of Cr, Ni, Cu, Zn, Pb, and Cd in aqueous samples. After extraction of the analytes by using the optimum conditions (sample volume: 25 mL, complexing agent: APDC, organic solvent: hexylbenzene, extraction time: 2 …

Synthesis Of Novel Chiral Bisoxazoline Ligands With A Norbornadiene Backbone: Use In The Copper-Catalyzed Enantioselective Henry Reaction, Rabi̇a Deli̇kuş, Emi̇ne Çakir, Nadi̇r Demi̇rel, Meti̇n Balci, Betül Karataş

Turkish Journal of Chemistry

Novel chiral bisoxazoline ligands based on norbornadiene were synthesized and used for the asymmetric Henry reaction. Various aromatic aldehydes were converted into chiral $\beta $-nitro alcohols with high yields and moderate to acceptable enantioselectivities under the optimized reaction conditions.

Modulation Of The Physiological And Biochemical Effects Of Copper Nanoparticles In Kidney Beans (Phaseouls Vulgaris) Treated By Kinetin, Suzanne Annette Apodaca

Open Access Theses & Dissertations

It is imperative to not only understand the impact of engineered nanomaterials (ENMs) in edible plants, but also the interactions they have with various additives used in agriculture. In this study, kidney bean plants were grown in potting soil treated with nano copper (nCu), bulk copper (bCu), and copper chloride (CuCl2) at concentrations of 0, 50, and 100 mg/kg for 55 and 90 days. At 15 days of growth, 0, 10, and 100 μm of kinetin (KN) were applied to plants. Plant tissue samples were harvested at 55 days and seeds were reaped at 90 days. Physiological and biochemical parameters …

Fabrication, Characterization, And Application Of Carbon Nanoparticles For The Detection Of Heavy Metal Ions In Aqueous Media, Aaron Michael Simpson

Graduate Theses/Dissertations

This research set out to develop a method for producing Carbon nanoparticles (CNPs) from glycerol and use them to detect Cu2+, Hg2+, and Pb2+ ions in aqueous solution. Three synthesis methods were developed using the following mixtures: (1) glycerol and silica, (2) glycerol, silica, and H3PO4, and (3) glycerol with H3PO4. The structure of the particles was characterized using a variety of spectroscopic techniques. Size distributions were obtained from scanning electron microscopy images. The particles were spherical with average diameters of 66, 58, and 89 nm respectively and believed to consist of a carbon core with carboxylic acid and alcohol …

Au Nanostructured Surfaces For Electrochemical And Localized Surface Plasmon Resonance-Based Monitoring Of Α-Synuclein-Small Molecule Interactions., Xin R Cheng, Gregory Q Wallace, François Lagugné-Labarthet, Kagan Kerman

Chemistry Publications

In this proof-of-concept study, the fabrication of novel Au nanostructured indium tin oxide (Au-ITO) surfaces is described for the development of a dual-detection platform with electrochemical and localized surface plasmon resonance (LSPR)-based biosensing capabilities. Nanosphere lithography (NSL) was applied to fabricate Au-ITO surfaces. Oligomers of α-synuclein (αS) were covalently immobilized to determine the electrochemical and LSPR characteristics of the protein. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed using the redox probe [Fe(CN)6](3-/4-) to detect the binding of Cu(II) ions and (-)-epigallocatechin-3-gallate (EGCG) to αS on the Au-ITO surface. Electrochemical and LSPR data were complemented by Thioflavin-T (ThT) …

Application Of Lipid Styryl Dye For Staining Intracytoplasmic Membranes In Gram-Negative Bacteria, Theodore J. Hammer

Williams Honors College, Honors Research Projects

Intracytoplasmic membranes are structures that form within cells which help facilitate a variety of different metabolic processes. This feature of intracellular membranes makes them particularly valuable for studying compartmentalization and cell dynamics in bacteria. In the past, transmission electron microscopy has been the primary method for imaging bacteria with intracytoplasmic membranes. Because transmission electron microscopy takes images of a cell in fixed slices, it’s impossible to follow a cell’s growth and development over time. Fluorescence microscopy is a particularly effective method of measurement that can combat these issues when evaluating live bacterial cells. Here, standard biochemical laboratory procedures were used …

Efficient C--C Cross-Coupling Reactions By (Isatin)-Schiff Base Functionalized Magnetic Nanoparticle-Supported Cu(Ii) Acetate As A Magnetically Recoverable Catalyst, Seyedeh Simin Miri, Mehdi Khoobi, Fatemeh Ashouri, Farnaz Jafarpour, Parviz Rashidi Ranjbar, Abbas Shafiee

Turkish Journal of Chemistry

Copper catalysts were simply fabricated through surface modification of superparamagnetic iron nanoparticles with indoline-2,3-dione(isatin)-Schiff-base and interaction with Cu from low-cost commercially available starting materials. Catalysts were characterized using atomic absorption spectrophotometry, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, UV/Vis spectroscopy, scanning electron microscopy, and transmission electron microscopy. These catalysts showed high efficiency for phosphine-free Mizoroki--Heck and Suzuki--Miyaura cross-coupling reactions with good diversity and generality. The catalysts could be easily recovered and reused several times without a significant loss in their catalytic activity and stability.

Electrodeposition Of Copper From A Choline Chloride Based Ionic Liquid, Rostom Ali M., Ziaur Rahman Md., Sankarsaha S.

Journal of Electrochemistry

The electrodeposition of copper from a solution containing copper chloride in either an ethylene glycol (EG)-choline chloride based or a urea-choline chloride based ionic liquid has been carried out onto a steel cathode by constant current and constant potential methods at room temperature. The influences of various experimental conditions on electrodeposition and the morphology of the deposited layers have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It is shown that very smooth, shiny and dense with good adherence and bright metallic coloured copper coatings can be obtained from both EG and urea based ionic liquids at …

Metal Ion Analysis For Use In Calculation Of Apparent Molar Volumes And Apparent Molar Heat Capacities Of Copper(Ii), Nickel(Ii), And Zinc(Ii) Nitrates, Eric Merkley, Dr. Earl M. Woolley

Journal of Undergraduate Research

Apparent molar heat capacity, Cp,f, and apparent molar volume, Vf, are valuable thermodynamic quantities in the study of solute-solvent interactions and chemical reactions in aqueous solutions. Work in our laboratory1-3 has demonstrated that fixed-cell differential scanning calorimetry (DSC) and vibrating-tube densimetry can provide sensitive and accurate data for calculating Cp,f and Vf. We have recently collected data for solutions of copper(II) nitrate, nickel(II) nitrate, and zinc(II) nitrate. As for most compounds, there is a lack of Cp,f and Vf date for these heavy metal nitrates. Our measurements will allow calculation of Cp,f and Vf.

Synthesis, Structural Variations And Trends In The Properties Of Unique Dinuclear And Polynuclear Complexes Of Bis(Pyrazolyl)Methane Ligands In Solid State And Solution, Andrea Eva Pascui

Theses and Dissertations

The semi-rigid ligands, p-[CH(pz)₂]₂C₆H₄, L_p, m-[CH(pz)₂]₂C₆H₂, L_m, and m-[CH(3,5-Me₂pz)₂]₂C₆H₄, L_m* (pz = pyrazolyl ring), link two bis(pyrazolyl)methane units into a single molecule by a rigid phenylene spacer and are used to study the structural variations and magnetic interactions in self-assembled first row, divalent transition metal complexes in polymeric, dinuclear and dinuclear metallacyclic settings. The formation of these architectures highly depend on the geometry of these ligands: anti, the …

Synthesis And Structures Of New Three-Dimensional Copper Metal-Organic Frameworks, Nitin Kumar Pally

Masters Theses & Specialist Projects

Metal-organic frameworks (MOFs) are crystalline materials with metal ions covalently bonded to organic ligands. The ligands act as spacers often creating a porous structure with very high pore volume and surface area. MOFs are known for their robust structures, high porosity, and different chemical functionalities and are considered for applications in adsorptions, separations, catalysis and gas storage. This work focuses on the synthesis of new MOFs using copper compounds. Different types of carboxylate ligands were used for the synthesis. Two new copper-organic frameworks, [Cu₃(pyz)(btc)] (1), and [(Cu₃(btc))•xH₂O] (2) (btc= benzene-1,3,5-tricarboxylate, pyz= pyrazine) have been …

Facile, Green Synthesis Of Large Single Crystal Copper Micro And Nanoparticles With Ascorbic Acid And Gum Arabic, Preston B. Landon, Alexander H. Mo, Carlos T. Ramos, Jose J. Gutierrez, Ratnesh Lal

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Large single crystal colloidal copper particles with diameters between 0.5 - 2 μm were created using a green synthesis process. The process used ascorbic acid to reduce Schweizer’s reagent created in situ using copper salts in the presence of various concentrations of gum arabic. The Schweizer’s reagents were created by varying the concentrations of ammonium hydroxide and copper nitrate solutions, copper hydroxide, or copper sulfate. The pH of the solution was controlled by the addition of ascorbic acid. Particle formation was favored at high temperature using copper sulfate at pH values ranging from 7.5 to 9, while the optimal formation …

Intramolecular Hydrogen Bonding In CuIi Complexes With 2,6-Pyridinedicarboxamide Ligands: Synthesis, Structural Characterization, And Physical Properties, Denan Wang, Sergey V. Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

The significance of second-sphere interactions in synthetic catalysts and metalloenzyme active sites has encouraged the development of ligand frameworks capable of supporting intramolecular hydrogen-bonding networks. With this approach in mind, we prepared a series of 2,6-pyridinedicarboxamide ligands (H₂L^X) that feature outer-sphere heterocyclic groups (pyridine, pyrimidine, or quinoline rings). Reaction with CuCl₂ yields complexes with the general formula [CuCl₂(L^X{H}₂)] (1^X), in which the pincer ligands coordinate to the Cu^II center in a tridentate fashion through the central pyridine and two amidato nitrogen atoms. The L^{X …}

A Study On The Structure And Photodetachment Dynamics Of Copper Based Molecular Anions Using Photoelectron Spectroscopy, Nicholas Stephen Holtgrewe

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation represents a study of the effects of electron molecule interactions in the detachment and dissociation dynamics of copper based molecular anions. Results are presented on the photodetachment of small copper oxide CuO_n⁻ (n = 1, 2) and copper fluoride CuF _n⁻ (n = 1, 2) molecular anions. Effects of different resonances are explored using the photoelectron angular distributions (PADs) and the relative intensity variations in vibrational channel cross sections. The specific resonances studied include dipole bound resonances, in which the electric dipole moment of the neutral molecule captures the outgoing electron, and electronic Feshbach resonances, …

Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor

Graduate Theses and Dissertations

Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …

Multiscale Modeling Of Enzyme-Catalyzed Methanol Production By Particulate Methane Monooxygenase, Katherine K. Bearden

Doctoral Dissertations

In this work, the conversion of methane to methanol by the particulate Methane Monooxygenase (pMMO) enzyme is investigated using a multi-scale modeling approach. This enzyme participates in carbon cycling and aids in the removal of harmful atmospheric methane, converting it to methanol. The interaction between pMMO and a neighboring enzyme that is present in the same organism is studied, and the unknown pMMO active site is elucidated and tested for methane oxidation towards the production of methanol.

Fundamental knowledge of pMMO's mechanism is not fully understood. Understanding how this enzyme works in nature will provide information towards designing efficient synthetic …

Metallization Of Dna And Dna Origami Using A Pd Seeding Method, Yanli Geng

Theses and Dissertations

In this dissertation, I developed a Pd seeding method in association with electroless plating, to successfully metallize both lambda DNA and DNA origami templates on different surfaces. On mica surfaces, this method offered a fast, simple process, and the ability to obtain a relatively high yield of metallized DNA nanostructures. When using lambda DNA as the templates, I studied the effect of Pd(II) activation time on the seed height and density, and an optimal activation time between 10 and 30 min was obtained. Based on the Pd seeds formed on DNA, as well as a Pd electroless plating solution, continuous …

Determination Of Copper Speciation, Bioavailability And Toxicity In Saltwater Environments, Tara N. Tait

Theses and Dissertations (Comprehensive)

The speciation of copper plays a strong role in determining bioavailability and toxicity upon copper exposure in marine environments. Specifically, natural organic matter (NOM) can complex with copper, influencing speciation and decreasing bioavailability. The aim of this research was to determine accurate copper speciation values using literature and new techniques and applying the techniques that reflect the most accurate speciation values to investigate the influence of NOM quantity and quality on copper speciation and toxicity. The results from this study will have implications on the development of a marine Biotic Ligand Model (BLM). Free copper was measured using a flow-through …

Underpotential Deposition Of Copper On Pt(S)[N(100)X(110)] Stepped Surfaces, Gisbert Rubn, Climent Vctor, Herrero Enrique, M. Feliu Juan

Journal of Electrochemistry

The underpotential deposition of Cu on platinum stepped surfaces composed of (100) terraces and (110) monoatomic steps has been studied in different acidic solutions. It has been found that the initial stage of copper deposition on the surface takes place simultaneously on terrace and step sites, irrespective of the nature of the adsorbing anion. During the voltammetric deposition of a full monolayer, several peaks can be observed. The analysis of the dependence of the peak charge with the step density allows assigning the different peaks to different deposition sites. The peak appearing at most positive potentials corresponds to the deposition …

Quality Assurance Plan Project For Copper Determination Using Flame Atomic Absorption Spectroscopy, Bharath Raparthi

All Capstone Projects

This study developed a method for determination of Copper by flame atomic absorption spectrometry (FAAS) from the soil samples and mine tailings using Perkin Elmer AAnalyst 800 atomic absorption spectrometer. A detailed procedure has been developed with a detection limit of 0.12 mg/L. In the recent decades, pollution from heavy metals has been increased. Copper is one of the trace metals that has a significant impact and carries risk to the human health. Calibration curve was established with working range 0.1 ppm to 5 ppm with a correlation coefficient of 0.9994. Over 50 environmental samples from the historic Copper mining …

Lipid Peroxides And Glutathione Status In Human Progenitor Mononuclear (U937) Cells Following Exposure To Low Doses Of Nickel And Copper, William Y. Boadi, Shalandus Harris, Justin B. Anderson, Samuel E. Adunyah

Chemistry Faculty Research

Effects of Cu2+, Ni2+ or Cu2+ + Ni2+ on lipid peroxide and glutathione (GSH) levels in U937 cells were investigated. Cells were treated with 0, 5, 10, and 20 µM of Cu2+ and/or Ni2+ and H2O2 (0.01 mM) and incubated for 24 hours at 37°C. Lipid peroxides were measured by the thiobarbituric acid assay (TBA). GSH intracellular levels were assayed by the GSH assay kit from EMD/Calbiochem (San Diego, California, USA). Cu2+ or Ni2+ significantly (P < 0.01) increased lipid peroxides in a dose-dependent manner, compared to controls. The effect was more pronounced for Cu2+, compared to the Ni2+-treated samples. Cu2+ + Ni2+ increased lipid peroxides in a significant (P < 0.001), dose-dependent manner, compared to Cu2+ or Ni2+ alone (i.e., ratio of 2.5:1-fold for combined versus single treatments, respectively). Cu2+ or Ni2+ significantly decreased GSH levels in U937 cells, with the effect being pronounced for Cu2+. Cu2+ + Ni2+ metal ions significantly (P < 0.001) depleted cells of GSH in a dose-dependent manner. Ethylene diamine tetraacetic acid (EDTA) at 50 or 100 µM moderately reduced the Cu2+- or Ni2+-induced effects on GSH levels. Interestingly, GSH levels generally decreased to half (except for the combined metal dose of 20 µM at 100 µM EDTA) of its level at the highest metal concentration tested for both the single or combined treatments. In conclusion, multiple exposures of cells to metal ions may be lethal to cells, compared to their single treatments.