Open Access. Powered by Scholars. Published by Universities.®

Physical Chemistry Commons™

Open Access. Powered by Scholars. Published by Universities.®

Analytical Chemistry

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 301 - 330 of 651

Full-Text Articles in Physical Chemistry

Two-Dimensional Interlocked Pentagonal Bilayer Ice: How Do Water Molecules Form A Hydrogen Bonding Network?, Weiduo Zhu, Wen- Hui Zhao, Lu Wang, Di Yin, Min Jia, Jinlong Yang, Xiao Cheng Zeng, Lan-Feng Yuan Jan 2016

Two-Dimensional Interlocked Pentagonal Bilayer Ice: How Do Water Molecules Form A Hydrogen Bonding Network?, Weiduo Zhu, Wen- Hui Zhao, Lu Wang, Di Yin, Min Jia, Jinlong Yang, Xiao Cheng Zeng, Lan-Feng Yuan

Xiao Cheng Zeng Publications

The plethora of ice structures observed both in bulk and under nanoscale confinement reflects the extraordinary ability of water molecules to form diverse forms of hydrogen bonding networks. An ideal hydrogen bonding network of water should satisfy three requirements: (1) four hydrogen bonds connected with every water molecule, (2) nearly linear hydrogen bonds, and (3) tetrahedral configuration for the four hydrogen bonds around an O atom. However, under nanoscale confinement, some of the three requirements have to be unmet, and the selection of the specific requirement(s) leads to different types of hydrogen bonding structures. According to molecular dynamics (MD) simulations …

Go to article

Near-Barrierless Ammonium Bisulfate Formation Via A Loop-Structure Promoted Proton-Transfer Mechanism On The Surface Of Water, Lei Li, Manoj Kumar, Chongqin Zhu, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng Jan 2016

Near-Barrierless Ammonium Bisulfate Formation Via A Loop-Structure Promoted Proton-Transfer Mechanism On The Surface Of Water, Lei Li, Manoj Kumar, Chongqin Zhu, Jie Zhong, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

In the atmosphere, a well-known and conventional pathway toward the formation of ammonium sulfate is through the neutralization of sulfuric acid with ammonia (NH3) in water droplets. Here, we present direct ab initio molecular dynamics simulation evidence of the formation of ammonium bisulfate (NH4HSO4) from the hydrated NH3 and SO3 molecules in a water trimer as well as on the surface of a water droplet. This reaction suggests a new mechanism for the formation of ammonium sulfate in the atmosphere, especially when the concentration of NH3 is high (e.g., ∼10 μg …

Go to article

Resolving The Hono Formation Mechanism In The Ionosphere Via Ab Initio Molecular Dynamic Simulations, Rongxing He, Lei Li, Jie Zhong, Chongqin Zhu, Joseph S. Francisco, Xiao Cheng Zeng Jan 2016

Resolving The Hono Formation Mechanism In The Ionosphere Via Ab Initio Molecular Dynamic Simulations, Rongxing He, Lei Li, Jie Zhong, Chongqin Zhu, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Solar emission produces copious nitrosonium ions (NO+) in the D layer of the ionosphere, 60 to 90 km above the Earth’s surface. NO+ is believed to transfer its charge to water clusters in that region, leading to the formation of gaseous nitrous acid (HONO) and protonated water cluster. The dynamics of this reaction at the ionospheric temperature (200–220 K) and the associated mechanistic details are largely unknown. Using ab initio molecular dynamics (AIMD) simulations and transition-state search, key structures of the water hydrates—tetrahydrate NO+(H2O)4 and pentahydrate NO+(H2O)5 …

Go to article

Probing The Structures Of Gold–Aluminum Alloy Clusters AuXAlY−: A Joint Experimental And Theoretical Study, Navneet S. Khetrapal, Tian Jian, Rhitankar Pal, Gary V. Lopez, Seema Pande, Lai-Sheng Wang, Xiao Cheng Zeng Jan 2016

Probing The Structures Of Gold–Aluminum Alloy Clusters AuXAlY−: A Joint Experimental And Theoretical Study, Navneet S. Khetrapal, Tian Jian, Rhitankar Pal, Gary V. Lopez, Seema Pande, Lai-Sheng Wang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Besides the size and structure, compositions can also dramatically affect the properties of alloy nanoclusters. Due to the added degrees of freedom, determination of the global minimum structures for multi-component nanoclusters poses even greater challenges, both experimentally and theoretically. Here we report a systematic and joint experimental/theoretical study of a series of gold–aluminum alloy clusters, AuxAly−(x + y = 7,8), with various compositions (x = 1–3; y = 4–7). Well-resolved photoelectron spectra have been obtained for these clusters at different photon energies. Basin-hopping global searches, coupled with density functional theory calculations, are used …

Go to article

Kinetic Decay Of A Polymer/Ink Complex As An O2 Indicator, Becca Hoene Jan 2016

Kinetic Decay Of A Polymer/Ink Complex As An O2 Indicator, Becca Hoene

All Master's Theses

Indicator inks are an important part of the continued consumption of packaged goods. This thesis is focused on understanding the kinetics and reaction mechanism for a unique indicator ink that is based upon the oxidation of indigotetrasulfonate (ITS) encapsulated in the polyelectrolyte poly(diallyldimethylammonium chloride) (polyDADMAC). Sodium bisulfite (NaHSO3) was used as the initial oxygen scavenger and to drive the reduction of the ITS. Studies were predominantly done in solution phase through the dilution of the ink systems. Fluorescence spectroscopy was the primary method used to determine the kinetic decay rates and interaction between the ITS dye molecules and …

Go to article

Improved High Temperature Stability Of Anatase Tio2 Photocatalysts By N, F, P Co-Doping, Rachel Fagan, Declan Mccormack, Steven Hinder, Suresh Pillai Jan 2016

Improved High Temperature Stability Of Anatase Tio2 Photocatalysts By N, F, P Co-Doping, Rachel Fagan, Declan Mccormack, Steven Hinder, Suresh Pillai

Articles

Among the three commonly occurring phases (anatase, rutile, and brookite) of TiO2, the anatase form is reported to be the best photocatalyst due to the improved charge-carrier mobility and the greater number of surface hydroxyl groups. The anatase to rutile transition in titania photocatalysts usually occurs at a temperature between 500 °C to 700 °C. Development of a high temperature stable (above 1000 °C) anatase phase is important for various environmental applications (e.g. self-cleaning ceramic tiles, anti-microbial sanitary wares, etc.). In this study, the use of ammonium hexafluorophosphate as a single source dopant (method A) and urea, trifluoroacetic acid and …

Go to article

Probing Allosteric, Partial Inhibition Of Thrombin Using Novel Anticoagulants, Stephen S. Verespy Iii Jan 2016

Probing Allosteric, Partial Inhibition Of Thrombin Using Novel Anticoagulants, Stephen S. Verespy Iii

Theses and Dissertations

Thrombin is the key protease that regulates hemostasis; the delicate balance between procoagulation and anticoagulation of blood. In clotting disorders, like deep vein thrombosis or pulmonary embolism, procoagulation is up-regulated, but propagation of clotting can be inhibited with drugs targeting the proteases involved, like thrombin. Such drugs however, have serious side effects (e.g., excessive bleeding) and some require monitoring during the course of treatment. The reason for these side effects is the mechanism by which the drugs’ act. The two major mechanisms are direct orthosteric and indirect allosteric inhibition, which will completely abolish the protease’s activity. Herein we sought an …

Go to article

Intercalation Of Clo4- Into Hopg Investigated By Ec-Stm, Xiao-Yan Hu, Alice Aliwowe, Jia-Wei Yan, Bing-Wei Mao Dec 2015

Intercalation Of Clo4- Into Hopg Investigated By Ec-Stm, Xiao-Yan Hu, Alice Aliwowe, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

The electrochemical intercalation and surface morphology of highly oriented pyrolytic graphite (HOPG) electrode in 2 mol⋅L-1 HClO4 were studied by in situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV). Based on the step-height changes observed before and after the intercalation, the effects of different step sites on intercalation are compared. The feasibility, reversibility and speed of intercalation are discussed. The intercalation ofClO4- into HOPG can be divided into three types depending on the number of graphite layers at the step site: When the layers of graphite are more than three, the intercalation becomes feasible; when …

Go to article

Application Of Pd/Graphene Modified Electrode In The Detection Of 4-Chlorophenol, Peng Shi, Bo-Xuan Wang, Quan-Lin Song, Hui Wang, Xin Liu, Zhao-Yong Bian Oct 2015

Application Of Pd/Graphene Modified Electrode In The Detection Of 4-Chlorophenol, Peng Shi, Bo-Xuan Wang, Quan-Lin Song, Hui Wang, Xin Liu, Zhao-Yong Bian

Journal of Electrochemistry

The Pd/graphene composites were synthesized by a modified Hummers method and NaBH4 reduction process, and then were characterized using XRD, SEM, XPS, and TEM. The Pd/graphene modified glassy carbon electrode (Pd/graphene/GCE) was prepared based on this method. Cyclic voltammetry was used to study the optimum operation conditions for the 4-chlorophenol detection. It was shown that the surface of the graphene was smooth and Pd nanoparticles were uniformly dispersed on graphene. The average particle size was calculated to be 6.5 ± 0.05 nm. These nanoparticles exhibited high catalytic activity and sensitivity toward chlorophenols. PBS with a concentration of 0.1 mol·L-1 …

Go to article

Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman Sep 2015

Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman

Chemistry Faculty Publications

Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air–solid interface under variable relative humidity (RH = 0–90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10–6 occurs for …

Go to article

Effect Of Adsorption Potential On Co Oxidation At Au@Pt Nanoparticles Electrodes, A Surface Enhanced Raman Spectroscopic Study, Pu Zhang, Yi Wei, Yong-Li Zheng, Yan-Xia Chen, Zhong-Qun Tian Aug 2015

Effect Of Adsorption Potential On Co Oxidation At Au@Pt Nanoparticles Electrodes, A Surface Enhanced Raman Spectroscopic Study, Pu Zhang, Yi Wei, Yong-Li Zheng, Yan-Xia Chen, Zhong-Qun Tian

Journal of Electrochemistry

The adsorption/oxidation of CO on the 55 nm [email protected] nm Pt nanoparticles electrode in both potentiodynamic and potentiostatic modes were investigated by surface enhanced Raman spectroscopy in a thin layer electrochemical flow cell under controlled mass transport, with the aim of clarifying the origin CO oxidation at lower electrode potentials (in current pre-wave region of corresponding cyclic voltammograms). Our results demonstrated that the CO oxidation kinetics differed significantly from the three kinds of different CO adsorption history, with almost no CO oxidation current in the pre-peak potential region after 0.35 VRHE CO adsorption with or without subsequent holding the …

Go to article

Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions, Mei Xu, Jing-Jing Wang, Zhi-Chao Huangfu, Ng Ying Wa, Yu-Han He, Zhao-Hui Wang Aug 2015

Broadband Sum-Frequency Generation Spectroscopic Invstigations Of Thiocyanate On Polycrystalline Au Electrode In Alkaline Solutions, Mei Xu, Jing-Jing Wang, Zhi-Chao Huangfu, Ng Ying Wa, Yu-Han He, Zhao-Hui Wang

Journal of Electrochemistry

Broadband sum frequency generation (BB-SFG) spectroscopy has been used to investigating the potential-dependent adsorption behaviors of thiocyanate ions on polycrystalline Au electrode in alkaline solutions. During the positive scan, a change in the Stark slope (dωC-N/dE) for C—N stretching mode can be observed in the range of -1.1 V ~ 0.2 V (vs. SCE), which implies that the orientation of adsorbed thiocyanate ions at Au electrode surface changes from N-bound (dωC-N/dE=45 cm-1·V-1) form to S-bound (dωC-N/dE = 16.2 cm-1·V-1 …

Go to article

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner Aug 2015

Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al2O3 nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …

Go to article

Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert Aug 2015

Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert

Chemistry Faculty Publications

Several potential new phosphorus-containing flame retardant molecules were evaluated for heat release reduction potential by incorporation of the molecules into a polyurethane, generated from methylene diphenyl diisocyanate and 1,3-propane diol. The heat release reduction potential of these substances was evaluated using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods to qualitatively evaluate their potential reactivity into the polyurethane prior to heat release testing. The functionality of the flame retardants was epoxide based that would potentially react with the diol during polyurethane synthesis. Flammability testing …

Go to article

Fundamental Studies Of Magnetoconvective Forces And Density Gradients In A Microfluidic Environment, Adam James Kreidermacher Jul 2015

Fundamental Studies Of Magnetoconvective Forces And Density Gradients In A Microfluidic Environment, Adam James Kreidermacher

Graduate Theses and Dissertations

Magnetoconvection is a promising phenomenon for developing new electrochemical-based microfluidic flow devices with unique capabilities, such as easily switching flow direction and adjusting flow speeds and flow patterns as well as avoiding bubble formation. In order to develop these devices it is necessary to study the underlying forces. Four contributions toward fluid flow were considered. The first and foremost is the magnetohydrodynamic force, which is the magnetic component of the Lorentz force and governed by the right hand rule. It generates the majority of the convention, and is the most well-known. The second is the gravitational force, which causes convection …

Go to article

The Investigation Of The Low Temperature Combustion Of Mesitylene And Tert-Amyl Methyl Ether By Synchrotron Photoionization Mass Spectrometry, Martin Yu-Hin Ng May 2015

The Investigation Of The Low Temperature Combustion Of Mesitylene And Tert-Amyl Methyl Ether By Synchrotron Photoionization Mass Spectrometry, Martin Yu-Hin Ng

Master's Theses

This thesis describes the combustion experiments performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) located at the Lawrence Berkeley National Laboratories (LBNL). The need for renewable fuel sources, the need for the study of their combustion in the contexts of homogenous charge combustion ignition (HCCI) engines can be found in Chapter 1. The components of the experimental set-up used throughout this thesis—time-of-flight mass spectrometer, Excimer laser, vacuum pumps and other components—and the components of ALS responsible in synchrotron radiation generation and processing—the linear accelerator, the booster ring, insertion devices, gas filters and monochromator are explained in …

Go to article

Diol-Mediated Versus Water-Mediated Proton Transfer Reactions, Angela Moses May 2015

Diol-Mediated Versus Water-Mediated Proton Transfer Reactions, Angela Moses

DePaul Discoveries

The triple-proton-transfer reactions of 8H-1,8-naphthyridin-2-one (8H-naph) have been investigated by employing different ab initio quantum mechanical methods. The proton transfer reactions studied were facilitated through an adjacent 1,3-propanediol molecule or two adjacent water molecules. Identical proton transfer reactions were studied using a model system of 8H-naph to investigate the validity of computational approaches that use model systems to study more complex systems. The solvent effects on the structures were investigated for comparison to the initial gas phase calculations. The potential energy, reaction force, and work profiles were studied along the intrinsic reaction coordinate to monitor the developing proton transfer reactions.

Go to article

Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing May 2015

Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing

Honors Scholar Theses

The Toxic Substances Control Act (TSCA) is the central form of chemical regulation existent in the United States today, yet scientists are often unaware or uncertain of its provisions. Violations of TSCA by unknowing chemists set industry and government unnecessarily at odds. A lecture on TSCA was developed for undergraduate students that uses the concept of green chemistry to promote interest and incentivize learning. Green chemistry methods are cleaner and less wasteful than traditional chemical ones, and many companies using them are at the forefront of technological innovation. The lecture explains both green chemistry and TSCA, includes company case studies, …

Go to article

Unraveling Structures Of Protection Ligands On Gold Nanoparticle Au68(Sh)32, Wen Wu Xu, Yi Gao, Xiao Cheng Zeng Apr 2015

Unraveling Structures Of Protection Ligands On Gold Nanoparticle Au68(Sh)32, Wen Wu Xu, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

New low-energy atomic structures of the thiolate-protected gold nanoparticle Au68(SH)32 are uncovered, where the atomic positions of the Au atoms are taken from the recent single-particle transmission electron microscopy measurement by Kornberg and co-workers, whereas the pattern of thiolate ligands on the gold core is attained on the basis of the generic formulation (or rule) of the “divide and protect” concept. Four distinct low-energy isomers, Iso1 to Iso4, whose structures all satisfy the generic formulation, are predicted. Density-functional theory optimization indicates that the four isomers are all lower in energy by 3 to 4 eV than the …

Go to article

A Bracketing Method For Proton Affinity Measurements Of Dehydro-And Didehydropyridines, Guannan Li Apr 2015

A Bracketing Method For Proton Affinity Measurements Of Dehydro-And Didehydropyridines, Guannan Li

Open Access Theses

Proton affinity (PA) is a fundamental property that is related to the structure and reactivity of a molecule. Currently, very few experimental PA values are available for organic radicals and none for biradicals. Equilibrium methods cannot be used for these measurements. The traditional bracketing method is based on monitoring reactions of different reference bases with known proton affinities with the protonated analyte for the occurrence of exothermic proton transfer to determine the upper and lower limits of proton affinity. However, the energy deposited into the precursor ions upon CAD when forming protonated radicals may cause endothermic proton transfer reactions occur …

Go to article

Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan Apr 2015

Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan

Open Access Dissertations

Gas-phase radical ion chemistry has attracted increasing research interest from the mass spectrometry (MS) society because it provides new capabilities in bio-analysis which often complements traditional MS methods developed from even-electron ions. Fundamental studies of biomolecule related radical species are essential to broadening the scope of radical chemistry and pushing the frontiers of its analytical applications. This dissertation mainly discusses the gas-phase chemistry of peptide sulfinyl radicals (-SO·), which has been rarely studied before. In order to establish an effective research approach, a method that can generate site-specific peptide sulfinyl radical ion has been developed. This method is based on …

Go to article

Novel Dna Electrochemical Biosensor For K-Ras Point Mutation Detection Based On Dna Polymerase I, Li-Qing Lin, Cheng-Fei Zhao, Zhou-Qian Jiang, Shao-Huang Weng, Xiao-Lan Xie, Xin-Hua Lin Feb 2015

Novel Dna Electrochemical Biosensor For K-Ras Point Mutation Detection Based On Dna Polymerase I, Li-Qing Lin, Cheng-Fei Zhao, Zhou-Qian Jiang, Shao-Huang Weng, Xiao-Lan Xie, Xin-Hua Lin

Journal of Electrochemistry

In this article, we developed a novel DNA electrochemical sensor for obtaining a current-time curve based on DNA polymerase I. The capture probes were fixed on the Au electrode by Au interacting with -SH, and then hybridized with the K-ras mutant target DNA as far as one base before the mutation site. After hybridizing the K-ras mutant or wild target DNA, the resulting assembly reacted with the dUTP-biotin in the presence of DNA polymerase I. Then avidin-HRP combined the dUTP-biotin on the electrode. The proposed electrode was applied for detection in TMB solution by electrochemical technology. The experimental results showed …

Go to article

A Novel Nitrite Sensing Electrode Based On Au/Fe3O4/Chitosan Nanocomposite, Ying Dong, Yong Wang, Huan-Huan Xing, Jian-Ying Qu Feb 2015

A Novel Nitrite Sensing Electrode Based On Au/Fe3O4/Chitosan Nanocomposite, Ying Dong, Yong Wang, Huan-Huan Xing, Jian-Ying Qu

Journal of Electrochemistry

A novel nitrite sensing electrode based on gold nanoparticles and iron oxides (Fe3O4) magnetic nanoparticles was fabricated with chitosan as the protective film on glassy carbon matrix. Experiment results showed that the sensing electrode exhibited good electrocatalytic activity toward oxidation of nitrite, and the oxidation peak current increased linearly with the concentration of nitrite varying from 5.0×10-6 to 2.0×10-3 mol·L-1 (R=0.9996) with a detection limit of 7.1×10-7 mol·L-1 (S/N=3). The sensing electrode exhibited good sensitivity, selectivity and repeatability.

Go to article

Electrochemiluminescence Assay Based On Bipolar Electrode For Bioanalysis, Mei-Sheng Wu, Jing-Juan Xu, Hong-Yuan Chen Feb 2015

Electrochemiluminescence Assay Based On Bipolar Electrode For Bioanalysis, Mei-Sheng Wu, Jing-Juan Xu, Hong-Yuan Chen

Journal of Electrochemistry

Bipolar electrodes (BPEs) are electronic conductors which are usually embedded into microchannels. The potential difference at the BPE/solution interface is obtained by applying a voltage at the two ends of the microchannel. When it reaches a critical value, the redox reaction takes place at both poles of the BPE simultaneously. Compared with other detection methods, the electrochemiluminescence (ECL) platform based on BPE possesses the advantages of concentration enrichment, high sensitivity, low cost, portable sensor system, no need for a light source, which is quite suitable for bioanalysis. This paper reviews the ECL-BPE strategy for bioanalysis and proposes the future research …

Go to article

Electrochemiluminescence Biosensors Based On The Signal Amplification Of Co-Reactants, Hai-Jun Wang, Li-Juan Xiao, Ying He, Xin-Ya Jiang, Ya-Li Yuan, Ying Zhuo, Ya-Qin Chai, Ruo Yuan Feb 2015

Electrochemiluminescence Biosensors Based On The Signal Amplification Of Co-Reactants, Hai-Jun Wang, Li-Juan Xiao, Ying He, Xin-Ya Jiang, Ya-Li Yuan, Ying Zhuo, Ya-Qin Chai, Ruo Yuan

Journal of Electrochemistry

Using co-reactants to enhance the luminous efficiency of luminophores is a common, convenient and effective method in the construction of the electrochemiluminescence (ECL) biosensors. However, the different methods of introducing co-reactants in the construction of the ECL biosensors will bring different amplification effects. In this review, several signal amplification methods through co-reactants are summarized: 1) Adding the co-reactants directly into the detection solution; 2) Immobilizing the co-reactants onto the electrode surface; 3) Using enzymatic reaction to generate co-reactants in situ around the electrode surface. And then, the outlook of the ECL signal amplification strategy is proposed on those bases.

Go to article

Sensitive Detection Of Hydroxyl Radical Based On Silver-Enhanced Gold Nanoparticle Label, Yan Yang, Peng Yu, Xiao-Hua Zhang, Jin-Hua Chen Feb 2015

Sensitive Detection Of Hydroxyl Radical Based On Silver-Enhanced Gold Nanoparticle Label, Yan Yang, Peng Yu, Xiao-Hua Zhang, Jin-Hua Chen

Journal of Electrochemistry

A novel DNA-based electrochemical sensor has been successfully constructed for sensitive detection of hydroxyl radical (·OH) based on the silver-enhanced gold nanoparticle label. Thiolated DNA1 was firstly immobilized on the gold electrode through Au—S bonds. The ·OH generated from Fenton reaction could induce serious oxidative damage of the DNA1 layer on the electrode surface. Then DNA2-functionalized gold nanoparticles (DNA2-AuNPs) were linked on the electrode through the hybridization between DNA2 and undamaged DNA1. Based on the catalytic reduction of silver ion by AuNPs, a silver layer was formed on the surface of AuNPs. The quantitative assay of ·OH was carried out …

Go to article

A Multi-Channel Electrochemical Immunosensing System With Polyhrp-Based Signal Amplification For The Detection Of Tumor Markers, Wang-Ping Deng, Yan-Zhi Dou, Jing Su, Lin Hao, Shi-Ping Song, Chun-Hai Fan Feb 2015

A Multi-Channel Electrochemical Immunosensing System With Polyhrp-Based Signal Amplification For The Detection Of Tumor Markers, Wang-Ping Deng, Yan-Zhi Dou, Jing Su, Lin Hao, Shi-Ping Song, Chun-Hai Fan

Journal of Electrochemistry

We have developed a multi-channel electrochemical immunosensing system for the detection of α-fetoprotein (AFP). The sensing system consisted of carbon screen-printed electrode (SPCE) arrays and polyHRP-based signal amplification probes. AFP antigens could bind to both capture antibodies immobilized on electrode arrays ant detection antibodies (anti-AFP IgG developed in rabbit). The anti-rabbit IgG conjugated to poly-horseradish peroxidase were used as a signaling probe to bind to the immuno-complex. The current signals were harvested by a home-made multi-channels electrochemical detector. AFP could be detected in the concentration ranges of 64 pg·mL-1 ~ 250 ng·mL-1. The detection limit was as …

Go to article

Fabrication And Application Of Cytochrome P450 Electrochemcial Biosensor In Drug Metabolism, Xuan Xu, Ju-Sheng Lu, Song-Qin Liu Feb 2015

Fabrication And Application Of Cytochrome P450 Electrochemcial Biosensor In Drug Metabolism, Xuan Xu, Ju-Sheng Lu, Song-Qin Liu

Journal of Electrochemistry

The process of drug metabolism plays an important role in drug efficacy and toxicity in vivo. Thus, the development of cheap, continent, rapid and high-throughput method for drug metabolism studies has great guiding significance for the design of new drugs, the determination of drug dosage and the detection of clinical drugs. Since the key role played by Cytochrome P450 (CYP450) in phase-I drug reaction, the constructed CYP450 enzyme biosensor can be used for the initial screening of drugs. It is found that the replacement of coenzyme NADPH with an electrode is to provide two electrons demanded in the catalytic reaction. …

Go to article

Electrochemical Detection Of L-Cysteine Based On Iron Phthalocyanine/Nitrogen-Doped Graphene Modified Electrodes, Jing-Jing Xiao, Hui-Ying Xu, Li Xu, Bao-Hong Liu Feb 2015

Electrochemical Detection Of L-Cysteine Based On Iron Phthalocyanine/Nitrogen-Doped Graphene Modified Electrodes, Jing-Jing Xiao, Hui-Ying Xu, Li Xu, Bao-Hong Liu

Journal of Electrochemistry

In this study, we report a facile method to develop FePc/N-G hybrid modified electrode for the detection of L-cysteine. The electrochemical sensor was characterized by cyclic voltammetry and amperometric response. The sensor exhibited a wider linear range with rapid response which has outperformed pure FePc/GCE, highlighting the important role of nitrogen doped graphene as substrate for improving the electrochemical response property.

Go to article

Noncovalent Interactions Between Alkali Metal Cation And Aza/Thia-Crown Macrocycles: Mass Spectrometric Techniques And Theoretical Studies, Calvin A. Austin Jan 2015

Noncovalent Interactions Between Alkali Metal Cation And Aza/Thia-Crown Macrocycles: Mass Spectrometric Techniques And Theoretical Studies, Calvin A. Austin

Wayne State University Dissertations

Macrocyclic complexes have been useful in understanding many systems encountered in biology, along with having widespread use in analytical, pharmaceutical, and synthetic chemistry. My goal was to provide a quantitative experimental and theoretical description of cation-aza-crown and thia-crown ether interactions with alkali metal cations. Infrared multiple photon dissociation (IRMPD) action spectroscopy and energy-resolved collision-induced dissociation (CID) techniques were used in conjunction with theoretical electronic structure calculations to characterize the structures, binding interactions, and stability of cation-aza-crown ether interactions. Quantum chemical calculations at several levels of theory were employed to characterize the structures and stabilities of the isolated cations and aza-crown …

Go to article

First Prev Next Last