Analytical Chemistry Commons^™

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 …

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.

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 …

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.

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 …

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 …

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. …

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.

Sulfidic Spring In The Gypsum Karst System Of Monte Conca (Italy): Chemistry And Microbiological Evidences, Marianna Messina, Tiziana Grech, Fiorenzo Fiorenza, Alessandro Marlettta, Pietro Valenti, Salvatore Petralia

International Journal of Speleology

Monte Conca Cave is a karst system placed in Messinian evaporites, consisting of an active cave and a resurgence located on the massif of Monte Conca, Campofranco within the "Riserva Naturale Integrale di Monte Conca". A sulfidic spring is located in the terminal gallery of the cave. To characterize the physical and chemical parameters of the Monte Conca cave and of the sulfidic spring, air temperature, relative humidity, water pH, and concentrations of dissolved sulfides, nitrates and sulfates were monitored. The high sulfide consumption rate in the sulfidic spring, evaluated by a kinetic study, suggests that biotic consumption is dominant. …

Chloroamino Acids As A Chemical Explanation For Viking Labeled Release Soil Activity On Mars, John C. Hironimus

STAR Program Research Presentations

The Viking missions to Mars, which took place in the 1970’s, performed several experiments on martian soil in an attempt to discern if there was microbial life present. In one set of experiments, a nutrient solution containing amino acids and organic substrates tagged with carbon-14 was injected into sample cells containing martian soil, and the evolution of labeled CO2 was monitored. The evolution of labeled CO2 indicated that there was a process occurring that broke down the nutrients in solution and released CO2 as a byproduct. Cellular metabolism releases CO2, so this result supported the idea of microbial life on …

An Investigation Of The Effect Of Mn2+ On The Fth1 Ire-Irp Complex, Eric Thomas Mendenhall

Theses, Dissertations and Capstones

Iron is a widely distributed metal found in almost every physiological system in nature, thus being an essential part of life. Iron homeostasis in the human body must be tightly regulated as iron is both beneficial and harmful to different cellular processes. Ferritin is a protein that has a prominent role in maintaining iron homeostasis via iron sequestration. Additionally, this protein itself is regulated by the Iron Responsive Element (IRE) and its interaction with an apoaconitase protein or the Iron Regulatory Protein (IRP). The binding of the IRP to this IRE, located on the 5’ untranslated stem loop region of …

Energetics, Structure, And Rovibrational Spectroscopic Properties Of The Sulfurous Anions Sno− And Osn−, Ryan C. Fortenberry, Joseph S. Francisco

Department of Chemistry: Faculty Publications

The SNO⁻ and OSN⁻ anions are shown in this work to be very stable negatively charged species in line with other recent work [T. Trabelsi et al., J. Chem. Phys. 143, 164301 (2015)]. Utilizing established quartic force field techniques, the structural and rovibrational data for these anions are produced. The SNO⁻ anion is less linear and has weaker bonds than the corresponding neutral radical giving much smaller rotational constants.OSN⁻ is largely unchanged in these regards with inclusion of the additional electron.The S–N bond is actually stronger,and the rotational constants of OSN⁻ versus OSN are …

The Importance Of Context: An Exploration Of Factors Influencing The Adoption Of Student-Centered Teaching Among Chemistry, Biology, And Physics Faculty, Travis J. Lund, Marilyne Stains

Department of Chemistry: Faculty Publications

Background: Research at the secondary and postsecondary levels has clearly demonstrated the critical role that individual and contextual characteristics play in instructors’ decision to adopt educational innovations. Although recent research has shed light on factors influencing the teaching practices of science, technology, engineering, and mathematics (STEM) faculty, it is still not well understood how unique departmental environments impact faculty adoption of evidence-based instructional practices (EBIPs) within the context of a single institution. In this study, we sought to characterize the communication channels utilized by STEM faculty, as well as the contextual and individual factors that influence the teaching practices …

Hfq Regulates Antibacterial Antibiotic Biosynthesis And Extracellular Lytic-Enzyme Production In Lysobacter Enzymogenes Oh11, Gaoge Xu, Yuxin Zhao, Liangcheng Du, Guoliang Qian, Fengquan Liu

Department of Chemistry: Faculty Publications

Lysobacter enzymogenes is an important biocontrol agent with the ability to produce a variety of lytic enzymes and novel antibiotics. Little is known about their regulatory mechanisms. Understanding these will be helpful for improving biocontrol of crop diseases and potential medical application. In the present study, we generated an hfq (encoding a putative ribonucleic acid chaperone) deletion mutant, and then utilized a new genomic marker-free method to construct an hfq-complemented strain. We showed for the first time that Hfq played a pleiotropic role in regulating the antibacterial antibiotic bio- synthesis and extracellular lytic enzyme activity in L. enzymogenes. Mutation of …

On The Nature Of Excited States In Ruthenium Complexes: Towards Renewable Energy, Ryan A. Thomas

Wayne State University Dissertations

The 77 K radiative properties (spectra, quantum yields and lifetimes) of ruthenium-polypyridyl complexes are investigated to better understand the effects of electronic mixing on metal-to-ligand-charge-transfer (3MLCT) excited state properties and how metal-centered (3MC) excited states affect the properties of potential ruthenium photosensitizers.The radiative rate of relaxation (kRAD) determines the maximum possible excited state lifetime when all other relaxation pathways are blocked (kn = 0 for all n  RAD). Thus, the excited state will relax only by means of an emission characteristic of the polypyridyl chromophore. kRAD is expected to increase as the excited state energy increases while the value …

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 …

Development Of Inlet And Vacuum Ionization Methods For Characterization Of Biological Materials By Mass Spectrometry, Beixi Wang

Wayne State University Dissertations

Inlet ionization and vacuum ionization are novel ionization methods to produce electrospray ionization (ESI)-like ions from the solid or liquid states, operating from atmospheric pressure (AP) or vacuum, without the use of voltage or the necessity of high energy input such as a laser or particle beam. The fundamental aspects were probed for better understanding of the novel ionization processes. Initial applications were attempted to utilize the novel ionization methods for fast, robust, and quantitative analyses.

For inlet ionizations (laserspray ionization inlet, LSII; matrix assisted ionization inlet, MAII; and solvent assisted ionization inlet, SAII), small (e.g. drugs) to large (e.g. …

Scale Up Isolation Of Aaptamine For In Vivo Evaluation Indicates Its Neurobiological Activity Is Linked To The Delta Opioid Receptor, Nicole L. Mcintosh, Eptisam Lambu, Laura Millan-Lobo, Fei Li, Li He, Phillip Crews, Jennifer L. Whistler, Tyler Johnson

Student Research Posters

Opioid receptors belong to the large superfamily of seven transmembrane-spanning (7TM) G protein-coupled receptors (GPCRs). As a class, GPCRs are of fundamental physiological importance mediating the actions of the majority of known neurotransmitters and hormones. The Mu, Delta, and Kappa (MOP, DOP, KOP) opioid receptors are particularly intriguing members of this receptor family as they are the targets involved in many neurobiological diseases such as addiction, pain, stress, anxiety, and depression. Recently we discovered that the aaptamine class of marine sponge derived natural products exhibit selective agonist activity in vitro for the DOP versus MOP receptor. Our findings may explain …

Unraveling The Mechanism Of Selective Ion Transport In Hydrophobic Subnanometer Channels, Hui Li, Joseph S. Francisco, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Recently reported synthetic organic nanopore (SONP) can mimic a key feature of natural ion channels, i.e., selective ion transport. However, the physical mechanism underlying the K⁺/Na⁺ selectivity for the SONPs is dramatically different from that of natural ion channels. To achieve a better understanding of the selective ion transport in hydrophobic subnanometer channels in general and SONPs in particular, we perform a series of ab initio molecular dynamics simulations to investigate the diffusivity of aqua Na⁺ and K⁺ ions in two prototype hydrophobic nanochannels: (i) an SONP with radius of 3.2 Å, and (ii) single-walled …

Medium-Sized Au40(Sr)24 And Au52(Sr)32 Nanoclusters With Distinct Gold-Kernel Structures And Spectroscopic Features, Wen Wu Xu, Yadong Li, Yi Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

We have analyzed the structures of two medium-sized thiolateprotected gold nanoparticles (RS-AuNPs) Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au₄₀(SR)₂₄ and Au₅₂(SR)₃₂ nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-AuNPs of two other prevailing Au-kernels identified from previous experiments, namely the Ino-decahedral kernel and icosahedral kernel. …