Analytical Chemistry Commons^™

An Aptasensor Based On Aunps/Pani/Tnts Nanocomposite For Electrochemical Detection Of Tobramycin, Yong-Ling Nong, Ni-Na Qiao, Ying Liang

Journal of Electrochemistry

A novel well-constructed electrochemical aptamer-based sensor for the detection of tobramycin was presented, using differential pulse voltammetry (DPV) as a detection technique and methylene blue(MB) as an electrochemical indicator. A glassy carbon electrode modified with a nanocomposite of Au nanoparticles/polyaniline/titania nanotubes (AuNPs/PANI/TNTs) was constructed as the electrode scaffold. The nanocomposite was characterized by transmission electron microscopy and X-ray photoelectron spectroscopy in detail. The results of cyclic voltammetry and electrochemical impedance measurements demonstrated that the AuNPs/PANI/TNTs nanocomposites can improve greatly the electron transfer on the interface. For the detection of tobramycin, the DPV results showed a linear relationship between the current …

A Microfluidic Paper-Based Analytical Device For Early Diagnosis And Prognosis Of Acute Myocardial Infarction, Lim Wei Yin

Student Works (2020-2029)

Acute myocardial infarction (AMI), also termed as heart attack, is often clinically screened by blood test through the measurement of cardiac biomarkers (i.e., troponin (T or I), creatine kinase (CK−MB) and myoglobin) and electrocardiography (ECG) changes which are presented to the hospital. However, the early diagnosis of AMI is challenging because the detection of biomarkers such as troponin (T or I) and CK−MB are only reliable at the intermediate and later stages (> 6 hours after chest pain onset), during myocardial injury and myocardial infarction. On the other hand, myoglobin often been used as early biomarker which is detectable within …

Evaluation Of The Mechanisms And Effectiveness Of Nano-Hydroxides, Wood And Dairy Manure-Derived Biochars To Remove Fluoride And Heavy Metals From Water, Anna Rose Wallace, Wenjie Sun Dr, Chunming Su Dr

Civil and Environmental Engineering Theses and Dissertations

The development of effective treatment processes for the removal contaminants, such as fluoride and heavy metals, from polluted water have been urgently needed due to serious environmental health and safety concerns. In this dissertation, a variety of materials including various (hydro)oxide nanomaterials, biochars and surface modified biochar were studied to evaluate their effectiveness and mechanism on removing fluoride or mixed heavy metals from water.

In the Chapter 2, this study investigated the adsorptive removal of fluoride from water using various (hydro)oxide nanomaterials, focusing on ferrihydrite, hydroxyapatite (HAP) and brucite, which have the potential to be used as sorbents for surface …

The Effects Of Temperature On The Yields Of Aliphatic And Aromatic Products From The Supercritical Pyrolysis Of 1-Octene, Elizabeth Anne Hurst

LSU Doctoral Dissertations

Prior to their combustion, fuels for future high-speed aircraft are expected to experience supercritical conditions, leading to the production of polycyclic aromatic hydrocarbons (PAH), precursors to solid carbonaceous deposits, via pyrolytic reactions. These solid deposits can clog fuel-transfer lines, causing unsafe aircraft operation. To prevent the formation of fuel-line deposits, it is critical to understand the reaction pathways that lead to PAH formation in the supercritical fuel pyrolysis environment.

To better understand the role of large 1-alkenes in PAH formation, supercritical pyrolysis experiments with model fuel 1-octene, a representative 1-alkene product from supercritical n-alkane pyrolysis, have been performed. The …

Primary Homogeneous Pathways Of Lignin Depolymerization In Gas Phase, Mohamad Barekati-Goudarzi

LSU Doctoral Dissertations

The unique decomposition pathways of hydrolytic lignin (HL) dissolved in acetone/water mixture and dispersed into gas phase has been investigated using two unique reactors. The first one is a non-isothermal continuous wave-IR CO₂ Laser Powered Homogeneous Pyrolysis (LPHP) and the second one is an isothermal Continuous Droplet Evaporation (CDE) reactor. Both of these reactors operated using atmospheric N₂ carrier gas. A temperature region of 400 – 550°C, and various residence time of 0.12-2 sec were chosen for CDE reactor. The temperature distribution in the LPHP reactor was evaluated via thermocouple measurements and validated by the method of “chemical …

Electrochemical Detection Of 4-Nitrophenol Based On Glassy Carbon Electrode Modified By Tio2Nps/Rgo Composite, Lin-Na Jiu, Yong-Qiang Cheng

Journal of Electrochemistry

4-nitrophenol (4-NP) has become factitious pollution, and presented a serious threat to the nature and human health. It is necessary to develop a convenient and fast detection method. In this work, the glassy carbon electrode modified by titanium dioxide nanoparticles (TiO₂NPs)/reduced graphene oxide (RGO) composite as an electrochemical sensor was studied for the trace detection of 4-NP. The morphology of the composite was characterized by scanning electron microscopy (SEM). The homogeneous mixing of titanium dioxide nanoparticles and reduced graphene oxide increased the specific surface area of the composite, and facilitated the electrochemical reaction of 4-NP. The electrochemical characteristics …

Modification And Optimization Of Conducting Polymer-Modified, Redox-Magnetohydrodynamics (R-Mhd) Pumping For Enhanced And Sustained Microfluidics Applications, Md Foysal Zahid Khan

Graduate Theses and Dissertations

In this work, a novel microfluidic pumping approach, redox-magnetohydrodynamics (R-MHD) has improved by materials and device optimization to use in lab-on-a-chip applications. In R-MHD, magnetic flux (B) and ionic current density (j) interacts to generate body force (FB) in between active electrodes, according to the equation FB = j×B. This unique fluid pumping approach is scalable, tunable, generates flat flow profile, and does not require any channels or valves. Pumping performance, such as speed scales with the ionic current density (j) and duration depends on the total charge (Q). The ionic current density (j) results from the conversion of electronic …

Potential For On-Site, Prosecutorial Evidence From Drug Residues Collected On Plasmonic Paper: A Pilot Study For Sers-Psi-Ms, Daniel S. Burr

Theses and Dissertations

Given the potential impact of improvements to on-site drug testing, as well as recent, successful displays of paper spray ionization mass spectrometry (PSI-MS) in this regard, this thesis pilots the implementation of Raman spectroscopy as a compliment to MS for field-based confirmatory drug testing. Surface enhanced Raman scattering (SERS) is utilized for applications to trace detection. Two-tiered analysis of individual drug samples is enabled using triangularly-cut plasmonic papers, from which both SERS and PS-MS analysis may be performed. Several drug compounds, representative of traditional and emerging drug types, are examined by these techniques, both separately and as a fully integrated, …

Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou

Journal of Electrochemistry

Single particle impact electrochemistry (SPIEC) has grown rapidly in recent years and shown great promise in the analysis of nanoparticle properties as well as the detection of biomolecules including DNA, RNA, protein, enzyme, bacteria, virus, vesicles and others. This minireview summarizes recent advances in electroanalytical applications of SPIEC according to different analytical methods, i.e., direct electrolysis of nanoparticles or labeled nanoparticles, direct electrolysis of soft particles encapsulated redox molecule, indirect electrochemistry of particles, area and diffusion blocking, and changes in current magnitude and collision frequency.

A Low Noise Temperature Control System For Nanopore-Based Single Molecule Analysis, Cheng-Yu Yang, Zhen Gu, Zheng-Li Hu, Yi-Lun Ying, Yi-Tao Long

Journal of Electrochemistry

Nanopore employs a single bio-molecule interface, which is a highly sensitive single-molecule detection technology for measuring single biomolecules such as DNA, RNA, protein, and peptide. The interaction between single molecule and nanopore is thermodynamically controlled. Therefore, it is urgent to precisely control the temperature of the nanopore system without introduction of any noise. In this paper, we have developed a low-noise temperature control system for single-molecule detection of nanopores to achieve precise regulation at the ambient temperature during measurements. The system utilizes the thermoelectric effect of the semiconductor refrigerating chip to heat or cool the detection chamber, while adopts electromagnetically …

Recent Advances In Nanofluidic Electrochemistry For Biochemical Analysis, Zhong-Qiu Li, Zeng-Qiang Wu, Xing-Hua Xia

Journal of Electrochemistry

Nanofluidics, as a young research field, has been receiving more and more attentions. It has been successfully applied in various fields including nanoscale separation, biochemical sensing and energy conversion. The development of nanofluidics is closely related to electrochemistry that can provide a driving force for the study of the material transport characteristics in nanopores/nanochannels. On the other hand, nanopores/nanochannels can creat a microenvironment for study of spatially nanoconfined electrochemistry. The combination of nanofluidics and electrochemistry has given rise to many new theories and technologies for single molecule/particle analysis and nanofluid manipulation. Herein, we provide a review of the recent progresses …

In Situ/Operando Visualization Of Electrode Processes In Lithium-Sulfur Batteries: A Review, Shuang-Yan Lang, Xin-Cheng Hu, Rui Wen, Li-Jun Wan

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries have been regarded as one of the most promising candidates for the next-generation energy storage devices. Fundamental understanding of the structure and evolution processes at electrode-electrolyte interfaces is essential to the further development. In this review, we summarize recent advances in the interfacial observations by means of various in situ/operando visualization techniques, including scanning probe microscopy (SPM), electron microscopy (EM), X-ray microscopy (XRM) and optical microscopy (OM). The real-time investigation provides important evidence for the morphology and component changes including S/Li₂S transformation, polysulfide dissolution on cathodes and Li/solid electrolyte interphase (SEI) evolution on anodes, which …

Surface-Enhanced Infrared Absorption Spectroscopy- Surface Sensitive In Situ Label-Free Spectroelectrochemistry, Lie Wu, Jian-Long Sun, Xiu-E Jiang

Journal of Electrochemistry

Surface-enhanced infrared absorption spectroscopy (SEIRAS), especially in attenuated total reflectance (ATR) mode, taking advantages of surface-enhancement and near-field optical effect of enhancing substrate, is a ultra-sensitive infrared spectroscopy, which could achieve surface-selected detection at a sub-monolayer level. Since the enhancing substrate could simultaneously serve as a working electrode, ATR-SEIRAS is a readily surface-sensitive in situ label-free spectroelectrochemistry technique. With the advantages of small influence from metal species on enhancement effect, good potential reversibility of spectra, simple surface selection rule and sensitivity to polar molecules, ATR-SEIRAS has been widely applied in the fields of orientation analysis and species identification of interfacial …

A Facile Strategy For Two-Step Fabrication Of Gold Nanoelectrode For In Vivo Dopamine Detection, Li-Hao Guan, Chao Wang, Wang Zhang, Yu-Lu Cai, Kai Li, Yu-Qing Lin

Journal of Electrochemistry

In vivo monitoring neurochemicals with microelectrode is invasive and the damage to brain tissue may inevitably cause disturbance signals physiologically to the measurement. It is of great importance to reduce the electrode size and to decrease the damage. This study demonstrates a novel nanoelectrode preparation methodology for in vivo monitoring dopamine (DA) fluctuation in the living brain of rats with high dependability. The fabrication process of the gold nanoelectrode involving a few minutes consists of only two steps: 1) growing gold nanoseeds on surface of tip of glassy capillary by ion sputtering; 2) wet depositing a continuous conductive gold film …

High-Efficiency Nitrite Sensor Based On Cop Nanowire Array, Fu-Ling Zhou, Xiao-Li Xiong, Xu-Ping Sun

Journal of Electrochemistry

Nitrite has a negative impact on the environment and human health. The long-term consumption of nitrite-containing foods has a carcinogenic risk. Therefore, the analysis and detection of nitrite are important. It is of great significance to develop high-efficiency electrocatalysts to achieve high sensitivity and selectivity for nitrite detection. The cobalt phosphide nano-array (CoP/TM) was obtained by hydrothermal and low-temperature phosphating. The electrochemical test results show that the constructed CoP/TM was a highly efficient electrochemical reduction nitrite catalyst with the excellent sensing performance and response time less than 3 s, as well as the linear detection range of 1.0 μmol·L^{-1 …}

Recent Progress Of Electrochemiluminescence Sensors Based On Electrically Heated Electrode, Hui-Fang Zhang, Yi-Ting Chen, Fang Luo, Zhen-Yu Lin, Guo-Nan Chen

Journal of Electrochemistry

Electrochemiluminescence (ECL) has broad application in the fields of environmental monitoring and biological analysis due to its intrinsic advantages such as excellent versatility, good detection sensitivity, and high specificity. The intensity of ECL can be influenced by temperature variation in the ECL quantum efficiency and the rate of electrochemical reaction. However, traditional temperature control is commonly realized through bulk solutions heating, which is complicated and unfavorable for detection when the volatile and thermally unstable materials existed. In order to address these problems, electrically heated electrodes are used to adjust the temperature desired. The major character of this technique lies in …

Application Of Nanomaterials In The Detection Of Volatile Organic Compounds In Exhaled Breath For Cancer Diagnosis, Wan-Qiao Bai, Xue-Zhi Qiao, Tie Wang

Journal of Electrochemistry

Volatile organic compounds (VOCs) generated in human body can reflect one’s health state, and numerous diseases are identified by some VOCs biomarkers. More recently, analyses of VOCs biomarkers from exhaled breath have turned into a research frontier worldwide because it offers a noninvasive way for diseases diagnosis. Various kinds of nanomaterials are used to enhance the performance of sensing techniques, and play an essential role in miniaturization detection. In this review, several kinds of nanomaterials (metallic, metal oxide, carbon-based, composites and MOFs-based materials) used in various VOCs detection methods, especially in VOCs sensors are summarized. Learning from the successful utilization …

Graphene-Like Secondary-Laser-Etched Polyimide Film Decorated With CuXO Nanocomposites: A Novel Electrode Substrate For Non-Enzymatic Glucose Sensors, Wan-Lin Dai, Zhi-Wei Lu, Jian-Shan Ye

Journal of Electrochemistry

In this work, a novel electrode substrate with graphene-like surface and Cu_xO nanocomposites derived from secondary-laser-etched polyimide (SLEPI) film was synthesized and applied in non-enzymatic glucose detection for the first time. Characterizations indicate that the as-prepared SLEPI/Cu_xO film electrode (SLEPI/Cu_xO-FE) possessed huge surface area, plentiful active sites and excellent electrocatalytic performance. The obtained sensor exhibited the high sensitivity and selectivity for glucose determination with a linear range of 0.05 mmol·L^-1 to 3 mmol·L^-1 and a detection limit of 1.72 μmol·L^-1 (S/N=3), which provides a simple, flexible and low-cost electrochemical sensor for …

A Dual Nanostructured Approach To Sers Amenable To Large-Scale Production, Kory Brian Castro

Chemistry & Biochemistry Theses & Dissertations

A SERS device was made using a dual-nanostructured surface comprised of silver nanoparticle and silver nanowires. The ability of each nanostructure to produce a uniform surface was characterized and the surface-enhanced Raman scattering (SERS) response of the resulting surfaces were examined using the reporter molecule 4-aminothiolphenol (ATP) and a 638 nm excitation laser.

A synthetic method was developed to produce silver nanowires with lengths of ~20 μm and diameters of ~100 nm with a narrow size distribution. The method utilized a simple, one-pot synthesis that is amenable to large-scale production. A selective precipitation method was used to the isolate the …

The Effects Of Reactant Concentration And Air Flow Rate In The Consumption Of Dissolved O2 During The Photochemistry Of Aqueous Pyruvic Acid, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

The sunlight photochemistry of the organic chromophore pyruvic acid (PA) in water generates ketyl and acetyl radicals that contribute to the production and processing of atmospheric aerosols. The photochemical mechanism is highly sensitive to dissolved oxygen content, [O₂(aq)], among other environmental conditions. Thus, herein we investigate the photolysis (λ ≥ 305 nm) of 10–200 mM PA at pH 1.0 in water covering the relevant range 0 ≤ [O₂(aq)] ≤ 1.3 mM. The rapid consumption of dissolved oxygen by the intermediate photolytic radicals is monitored in real time with a dissolved oxygen electrode. …

Multidimensional Mass Spectrometry Of Chemonic™ Ccg-6 Nonionic Surfactant With Separation By Polarity And Shape, Charles Johnson

Williams Honors College, Honors Research Projects

Chemonic™ CCG-6 surfactant is a water-soluble poly(ethylene glycol) (PEG) conjugated alkyl glyceride emollient. This surfactant exists as a complex mixture of a glycerol cores conjugated with poly(ethylene glycol) branches (PEGylation) that were partially esterified with caprylic (C8) and capric (C10) acids. These may be esterified on one, two, or all three arms of the glyceride. The architecture of the structures in this mixture was studied using multidimensional mass spectrometry (MS). Mass spectrometry was interfaced with ultra-performance liquid chromatography (UPLC) and ion mobility (IM) separation. The mixture was separated by reversed-phase LC, oligomers of the star-branched polymer were separated according to …

The Pilot Application Of Electrochemical Impedance Spectroscopy On Dynamic Proton Exchange Membrane Fuel Cell, Jian-Wei Guo, Jian-Long Wang

Journal of Electrochemistry

By analyzing Electrochemical Impedance Spectroscopy (EIS) in applications of dynamic proton exchange membrane fuel cell (PEMFC), bottlenecks which restrict EIS tool development have been pointed out in this paper. Though the high-frequency resistance in EIS is largely accepted as cell inner-resistance, this can only be applied for cell with low current. The low-frequency resistance is difficult to be realized due to its relation with mass transfer. Furthermore, the improved Randles equivalent circuits are built up preliminarily, thus, penetrating into studies for mass transfer reaction, cell operation/degeneration, and high temperature fuel cell. Inspiringly, EIS is becoming an analyzing tool for stack …

Synthesis Of Keggin Polyoxometalates Modified Carbon Paste Electrode As A Sensor For Dopamine Detection, Peng-Fei Dong, Na Li, Hai-Yan Zhao, Min Cui, Cong Zhang, Ju-Jie Ren, Xue-Ping Ji

Journal of Electrochemistry

Polyoxometalates, a class of anionic clusters with structure diversity and size variability, make them very attractive in many fields such as electrochemistry, catalysis and medicine. The Co(C₁₅N₆H₁₂)₂[PW₁₂O₃₈]·5H₂O(Co[PW₁₂O₃₈]) modified carbon paste electrode was prepared in this work, and its electrochemical performances as the sensor for dopamine detection were characterized with electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. The preparation conditions and test conditions were optimized respectively. Under the optimized conditions, the POMs modified carbon paste electrode exhibited good selectivity and sensitivity …

Photocatalytic Activity: Experimental Features To Report In Heterogeneous Photocatalysis, Md. Ariful Hoque, Marcelo I. Guzman

Chemistry Faculty Publications

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic …

Cross Photoreaction Of Glyoxylic And Pyruvic Acids In Model Aqueous Aerosol, Sha-Sha Xia, Alexis J. Eugene, Marcelo I. Guzman

Chemistry Faculty Publications

Aerosols of variable composition, size, and shape are associated with public health concerns as well as with light-particle interactions that play a role in the energy balance of the atmosphere. Photochemical reactions of 2-oxocarboxylic acids in the aqueous phase are now known to contribute to the total secondary organic aerosol (SOA) budget. This work explores the cross reaction of glyoxylic acid (GA) and pyruvic acid (PA) in water, the two most abundant 2-oxocarboxylic acids in the atmosphere, under solar irradiation and dark thermal aging steps. During irradiation, PA and GA are excited and initiate proton-coupled electron transfer or hydrogen abstraction …

Carbon Composite Fe3O4 Nanoparticles Based Electrochemical Sensor For Hydrogen Peroxide Detection, Si-Yu Zhang, Hui-Juan Wang, Shu-Fang Li, Jian-Ying Qu

Journal of Electrochemistry

In this work, a novel hydrogen peroxide electrochemical sensor was constructed with ferroferric oxide (Fe₃O₄) magnetic nanoparticles, which demonstrated good electrocatalytic activity for hydrogen peroxide. There existed a good linear relationship between the concentration of hydrogen peroxide and the oxidation peak current in the range of 1.00 × 10^-6 ~ 1.00 × 10^-3 mol·L^-1 (R = 0.9980) with the detection limit of 6.60 × 10-7 mol·L^-1. The sensor exhibited good anti-interference ability, high reproducibility and stability.

Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera

Graduate Theses and Dissertations

A new microdialysis sampling method and microfluidic device were developed in vitro. The method consisted of using up to four microdialysis sampling probes connected in series to evaluate the relative recovery (RR) of different model solutes methyl orange, fluorescein isothiocyanate (FITC)-dextran average mol. wt. 4,000 (FITC-4), FITC-10, FITC-20, and FITC-40. Different flow rates (0.8, 1.0, and 1.5 µL/min) were used to compare experimentally observed relative recoveries with theoretical estimations. With increasing the number of probes in series, the relative recovery increases and ~100% (99.7% ± 0.9%) relative recovery for methyl orange was obtained. For larger molecules such as fluorescein isothiocyanate …

Simulation Analysis In Dynamic Performance Of Proton Exchange Membrane Fuel Cell Under Starting Condition, Yan Xiao, Ying-Jie Chang, Wei Zhang, Qiu-Hong Jia

Journal of Electrochemistry

Based on the equivalent circuit model, by considering both the dynamic gas pressure model and the dynamic heat transfer model, a lumped parameter model is developed. The start process of the fuel cell is simulated by using SIMULINK software. The undershoot of the voltage is observed from the simulation results, and the response time of the voltage is basically the same as that of the fuel cell temperature, which indicates that the temperature has great influence on the dynamic performance of the fuel cell. From the perspective of the temperature, the dynamic responses of the thermodynamic potential, the activation overvoltage, …

Nanoporous Carbon-Based Co2 Reduction Catalysts: Exploring The Combined Effects Of Surface Chemistry And Porosity, Wanlu Li

Dissertations, Theses, and Capstone Projects

For the first-time sulfur-doped, nitrogen-doped and sulfur, nitrogen-codoped nanoporous carbons were systematically studied as catalysts for CO₂ electrochemical reduction reaction (CO₂ERR). The Faradaic efficiencies (FE) of CO and CH₄ formation were calculated to evaluate the performance of these carbons. The best catalysts showed the FE of CO and CH₄ formation of 29% and 0.76%, respectively. It was found that the overall performance in CO₂ERR dramatically increased upon the reduction pretreatment of the carbons in N₂-saturated electrolyte before the CO₂ reduction process. The pretreated carbon showed the maximum FE of CO …

Technology Development For Detection Of Circulating Disease Biomarkers From Liquid Biopsies Using Multifunctional Nanomaterials, Mustafa Balcioglu

Legacy Theses & Dissertations (2009 - 2024)

Despite the advance health care, devastating health conditions such as cancer and infectious diseases that affect populations worldwide are too often not diagnosed until morbid symptoms become apparent in the late phase. Obtaining an early and accurate diagnosis that reveal a hidden lethal threat before the disease becomes complicated may dramatically reduce the severity of its impact on the patient’s life and increase the probability of survival. For example, in the case of ovarian cancer, which is the fifth most common malignancy and the fifth leading cause of cancer mortality in women in the US, the 5-year relative survival is …