bluuebunny/crossref_metadata_2025 huggingface dataset:
(Keynote) Expression / Functional Activity Relationship of Multidrug Resistance-Associated Protein 1 Investigated By Scanning Electrochemical Microscopy
Authors: Mauzeroll Janine , Polcari David , Hernandez-Castro Javier , Li Kebin , Geissler Matthias
Published: February 2020

Cancer cells can develop multidrug resistance (MDR) after prolonged exposure to chemotherapeutic drugs, which is a severe impediment to successful treatment. MDR is typically associated with transmembrane proteins mediating efflux of administered drugs, thereby keeping their intracellular concentration below the threshold required to kill cells. Although expression assays based on flow cytometry and immunostaining have shown that multidrug resistance-associated protein 1 (MRP1) is prevalent in many cancer types, the functional activity of this efflux pump is more difficult to elucidate, especially at the single-cell level. Herein, we report the measurement of MRP1 functional activity in individual cancer cells using scanning electrochemical microscopy (SECM). Cells were cultured onto plastic substrates containing selective adhesion sites. Optical microscopy and SECM revealed that cells adapt to the underlying surface, while MRP1 functional activity increases once the dimensions of the adhesive islands become smaller than those of the cell itself. Time-lapse SECM imaging revealed a suitable window of 30 min to complete each measurement before the cell undergoes blebbing, which is associated with considerable increase in functional activity. Distinct cell populations were produced by performing a doxorubicin drug challenge on two parental cell lines (e.g., wild-type HeLa cells and MRP1-overexpressing HeLa-R cells). Expression and functional activity of MRP1 were determined using flow cytometry and SECM, and our findings show that these parameters do not directly correlate. This suggests that functional activity may represent a powerful indicator of a cancer cell’s response to chemotherapeutic treatment and should improve our understanding of efflux mechanisms based on MRP1.
Finite Element Simulation of the Coreactant Electrogenerated Chemiluminescence Mechanism
Authors: Danis Andrew , Odette William L , Perry Samuel C , Canesi Sylvain , Sleiman Hanadi F , Mauzeroll Janine
Published: February 2020

Electrogenerated chemiluminescence (ECL) is an electron transfer between redox products formed at an electrode that results in the formation of an excited state species, which is capable of photon emission. This excited state can be achieved by a reaction between an oxidized and a reduced form of the same luminophore, or via the reaction of the oxidised or reduced luminophore with an electrochemically generated co-reactant. This is of great interest to the biosensing community, as the attachment of multiple ECL-active luminophores to a target molecule is a very attractive signal amplification strategy. This is a complicated process involving multiple reaction steps, and so a thorough understanding of the complete reaction process and the evolution of the excited state luminophore is essential.

In order to gain a greater understanding of the ECL mechanism, we use finite element digital simulations to explicitly model each reaction step. This was done for an organometallic ECL standard, tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)3
2+), and tripropylamine (TPA), where the simultaneous oxidation of Ru(bpy)3
2+ and TPA result in the generation of the excited state Ru(bpy)3
2+*. The geometry and reaction conditions were chosen to match experimental data from our previously developed cuvette based system. Comparison of simulated voltammetry and ECL emission both agreed well with the experimental data, validating the experimental results and also giving insight into the impact of the confined cuvette geometry on the observed voltammetry. Investigations into the simulated concentration profiles also revealed the ECL emission to be confined close to the electrode surface, and so the impact of side reactions at the counter electrode could be omitted. Importantly, each step in the ECL process could be individually analysed and quantified in order to provide a greater understanding of the mechanism as a whole.

Figure 1: A) Simulated concentration of the excited state luminophore Ru(bpy)3
2+* at the position of peak ECL emission. B) Comparison of the experimental ECL emission peak with the simulated concentration of Ru(bpy)3
2+*, showing good agreement.

Figure 1
(Invited) Carbon Dioxide Solvation and Transport in Molten Carbonates
Authors: Corradini Dario , Coudert François-Xavier , Vuilleumier Rodolphe
Published: February 2020

Molten carbonates have properties of interest for practical use as electrolytes: they are highly conductive materials that remain liquid over a wide range of temperature and pressure and can dissolve very efficiently volatiles like water and carbon dioxide. Molten carbonates are nowadays successfully used as electrolytes in Molten Carbonate Fuel Cells (MCFC), with systems reaching 60 MW. They are also good candidates for electroreduction of CO2 as potential Carbon Capture and Storage (CCS) devices, for which there are already small scale attemps. Understanding the reactivity, speciation and transport of CO2 in molten carbonates is crucial for optimising the design of these devices. Here, we present atomistic simulations of molten carbonates and of CO2 dissolved in them. We show that CO2 interacts in a very specific way with the carbonate anions, forming transiently a new species, the pyrocarbonate anion C2O5
2-. This property explains the very high solubility of CO2 in molten carbonates compared to other molten salts. We also demonstrate that through the equilibrium between CO2 and C2O5
2-, the identity of CO2 is quickly lost through O2- exchanges. The transport of CO2 in molten carbonates thus occurs through a Grotthus type mechanism, leading to CO2 diffusion being three times faster that anion or cation diffusion. We will further discuss some consequences of these findings for CO2 electrolysis in molten carbonates.
Electrocatalytic Reduction of Carbon Dioxide at Network Films of Metallic Centers Generated within Supramolecular Ligands
Authors: Wadas Anna , Frik Malgorzata , Rutkowska Iwona Agnieszka , Kulesza Pawel J
Published: February 2020

The catalytic reductive transformation of carbon dioxide (CO2) to fuels and commodity chemicals is one of the most important contemporary energy and environmental challenges. Because CO2 is very stable, the direct electroreduction of CO2 to CO requires large over-potentials. Different approaches to electrocatalytic reduction of CO2 have been reported previously.

Copper is commonly considered out of the majority of metals, and it has often been studied in aqueous solutions. Among important issues is that it induces the cleavage of the C-O bonds in CO2 and it allows the formation of highly reduced products. Due to the unique properties of Cu toward CO2 reduction, systems in which this is employed have received the greatest degree of interest with respect to the catalytic effects in aqueous and organic electrolytes. In this work, CO2 reduction was investigated in the presence of new copper complex, in addition to the parallel studies on bimetallic copper-gold complex with the particular focus on the roles of particular metallic centers on the catalyst activity for the carbon dioxide reduction reaction..

A rotating ring (platinum)-disk (glassy carbon) electrode is employed for the characterization of different catalysts during CO2-electroreeduction in aqueous solutions.

In the process of electrochemical reduction of carbon dioxide, we have also concentrated on the catalytic system yielding nanostructured metallic palladium via reduction of the complex of palladium(II), [Pd(C14H12N2O3)Cl2]2∙MeOH. The catalytic activity of CO2 reduction was estimated from the oxidation charge of the adsorbed products. The adsorbed products obviously interfere with the formation of the oxide film on the Pd surface.

Mechanistic considerations will be a subject of our interest too. The results of XPS and IR studies will be used o comment on the surface identity of palladium based catalysts and possible reaction pathways.
(Invited) Photo-Electrochemical CO2 Reduction on Composite Metal and Metal-Oxide Cathodes
Authors: Augustynski Jan , Solarska Renata
Published: February 2020

Following the first report by Hori et al.1 that demonstrated ability of Group IB (11) based metal cathodes – copper, silver and gold – to promote electro-reduction of CO2 to gaseous products, substantial work has been subsequently devoted to the question of the electrodes deactivation occurring over prolonged electrolysis runs. Although the deactivation affects both an Au and an Ag cathode, where the CO2 reduction leads to the formation of CO, the most severe poisoning occurs in the case of the Cu where production of hydrocarbons (CH4, C2H4) and ethanol is practically suppressed after less than 1 h of electrolysis and become replaced by H2 evolution. SERS measurements conducted during electro-reduction of CO2 on the Cu surface suggest formation of a mixture of copper oxide/hydroxide and carbonate species as being the reason of the observed electrode deactivation. Among the means allowing activation of the cathodes are: short periodic potential cycling, implementation of composite (metal alloy, metal/oxide) electrodes, incorporation into the cathode of plasmonic metal nanostructures. Notably, it was in the case of the roughen silver electrode that the plasmon decay-induced CO2 reduction has been demonstrated for the first time2.

1. Y. Hori, K. Kikushi, S. Suzuki, Chem. Lett. 1695 (1985).

2. J. Augustynski, K. Bienkowski, R. Solarska, Coord. Chem. Rev. (2016).
Bio-Electrocatalytic CO2 Reduction into Formate Using Metal-Independent Formate Dehydrogenase from Candida Boidinii (Yeast)
Authors: Jayathilake Buddhinie Srimali , Narayanan S. R.
Published: February 2020

Rising levels of carbon dioxide (CO­2) in the atmosphere is a leading cause for global climate change. To reduce the level of CO2 in the atmosphere, the reduction of carbon dioxide into useful organic compounds and fuels is attractive. However, due to the inertness and stability of carbon dioxide molecule, the electro-reduction of carbon dioxide is not facile. Formate is the first stable intermediate in the electrochemical reduction of carbon dioxide. Further, formic acid is useful as a chemical feedstock, a fuel, and an efficient carrier of hydrogen.1-2 The production of formate is expected to be facile compared to that of other organic compounds as it involves the formation of just a C-H bond without dissociation of the strong C-O bond.

We have studied the interconversion of CO2 and formate using metal-independent type enzyme, Formate Dehydrogenase (FDH) derived from the yeast Candida boidinii. This enzyme relies on cofactors such as nicotinamide adenine dinucleotide phosphate (NAD(P)+/ NAD(P)H). To achieve steady-state electrolysis, we have examined the continuous electrochemical regeneration of the reduced form of NAD(P) cofactor. However, we find that formation of an inactive-stable dimer of NAD is a major obstacle to continuous electrolysis. Thus, we have focused on using methyl viologen (MV) as an artificial co-enzyme in conjunction with FDH. MV has the advantage of not being de-activated upon re-generation and also prevents the re-oxidation of formate to carbon dioxide.3

MV in its reduced form was synthesized in a three-electrode system using Toray paper working electrode, platinum counter electrode and Ag/AgCl reference electrode at 0.45 V vs NHE. The concentration of MV in its redox states was followed by scanning voltammetry using a carbon fiber microelectrode (Figure 1). CO2reduction to formate by the reduced form of the MV in the presence of FDH was investigated in this study. Formate production was confirmed by NMR. The presentation will discuss effect of enzyme concentration, carbon dioxide source and pH on the rate of production of formate.

Acknowledgement:

Authors acknowledge Loker Hydrocarbon Research Institute and University of Southern California for financial support of this work.

Refernces:

1.Olah, G. A.; Goeppert, A.; Prakash, G. S., Beyond oil and gas: The Methanol Economy. John Wiley & Sons: 2011.

2.Narayanan, S.; Haines, B.; Soler, J.; Valdez, T., Electrochemical conversion of carbon dioxide to formate in alkaline polymer electrolyte membrane cells. Journal of The Electrochemical Society
2011,
158(2), A167-A173.

3.Noji, T.; Jin, T.; Nango, M.; Kamiya, N.; Amao, Y., CO2 Photoreduction by Formate Dehydrogenase and a Ru-Complex in a Nanoporous Glass Reactor. ACS Applied Materials & Interfaces
2017,
9 (4), 3260-3265.

Figure 1
Analyzing the Electrochemically Catalytic Activity of Edge-Isolated MoS2 Monolayer
Authors: Liu Xiangye , Li Baichang , Qin Qianhui , Mottadecastro Emile , Hone James , Esposito Daniel V
Published: February 2020

Two dimensional (2D) MoS2 has been extensively studied as an efficient low-cost electrocatalyst for hydrogen evolution reaction (HER) and CO2 reduction reaction. Although the edges of MoS2 are known as the most active sites, the terraces sites can also be active due to the existence of defects. Designing edge-isolated and terrace-isolated platforms for MoS2 are essential to separately investigate their activities, which has not been done before. In our current project, those platforms have been achieved on MoS2 monolayer by using photolithography or E-beam lithography method. The HER activity of the edge was demonstrated to be 4 order magnitude higher than the terraces. Their activity benchmarks can be established. By those platforms, doping effects and heterostructure with other 2D materials can be also studied, in order to optimize the activities of the edge and terrace sites on MoS2.
Factors That Limit the Performance of CO2 Electrolyzers
Authors: Yang Hongzhou , Liu Zengcai , Sajjad Syed D. , Gao Yan , Kaczur Jerry J. , Masel Rich
Published: February 2020

Carbon dioxide (CO2) electrolysis provides a pathway to turn waste CO2 into valuable fuels and chemicals but most previous efforts demonstrate low selectivity, high overpotential and low rates for the targeted products. In recent work Dioxide Materials has been using Sustainion™ imidazolium functionalized membranes and ionomers to improve the performance. Runs at a fixed current density of 200 mA/cm2 showed that one can maintain 98% selectivity for six months at about 3 V applied potential, with a voltage increase of only 5 µV/hour. Other runs showed stable performance at 400 and 600 mA/cm².

Present areas for improvement of the technology include a better understanding of the processes that are occurring on the cathode catalysts, improving response to process upsets, developing cell designs that can be scaled to the m2 size and alternates to iridium as an anode catalyst. Initial work on these issues will be discussed.
Experimental and Computational Study on the Stability of Nitrogen, Boron, and Sulfur Doped Carbon Catalysts for Oxygen Reduction Reaction
Authors: Naumov Olga , Naumov Sergej , Abel Bernd , Varga Aron
Published: February 2020

A new approach in electrode catalysis bearing immense potential for electrochemical technologies is the prospect of carbon based electrodes. Pristine carbon nanostructures are relatively inert and modications including nitrogen, boron, sulfur doping and their combinations are known for their beneficial effects on the electrochemical activity of carbon nanomaterials in both alkaline and acidic media. However, long-term stability of these materials, especially in acidic environment, is rarely mentioned. Here, we evaluate the stability and longterm degradation of nitrogen (N), sulfur-nitrogen (SN), and boron-nitrogen (BN) co-doped graphene akes as oxygen reduction electrocatalyst with theoretical and experimental techniques. We assume that nitrogen dopants in the graphene sheet interact with electrons and protons at the electrode-electrolyte interface leading to ammonia scission and continuous catalyst deactivation. We analyse and compare the ammonia scission pathways of N, BN and SN containing graphene structures by the use of Density Functional Theory (DFT) B3LYP method. The stability of the model systems with regard to the investigated reaction pathway are correlated with the HOMO-LUMO energy separation, spin and charge densities showing that degradation of doped graphene and oxygen reduction reaction is driven by similar material parameters. The computational results are corroborated with electrochemical measurements at SAFC operating conditions.

Figure 1
Understanding and Designing Novel H- Ionic Conductors Based on First Principles Calculations
Authors: Bai Qiang , Mo Yifei
Published: February 2020

In contrast to proton (H+) conductor materials, hydride ion (H-) conductors are exceedingly rare in nature. Hydride ions are attractive charge carriers with a strong reducing property comparable to that of Mg, indicating potential high voltage and high energy densities. Recently, pure H- conduction in new La2-x-ySrx+yLiH1-x+yO3-y oxyhydrides has been demonstrated in experiments, opening a promising avenue for exploring new battery chemistry based on hydride ions. In this presentation, we will elucidate the H- diffusion mechanism in the distinctive structures of these new oxyhydrides, using first principles calculations. On the basis of our newly gained understandings of H- diffusion, we performed first principles computation to further optimize and design the oxyhydrides with enhanced properties. Our study demonstrated first principles computation approach for in-depth understanding of new materials and accelerated materials designing with enhanced properties, and is highly transferable to other materials.
Density Functional Theory Study of the Interactions of OH and Cl with the Pristine and Defective Surfaces of α-Fe2O3 (0001)
Authors: Pang Qin , DorMohammad Hossein , Isgor O. Burkan , Árnadóttir Líney
Published: February 2020

Fe (III) oxides have been identified as a dominant structure of the outer layer of the iron passive film formed in alkaline environment but chloride ion has been suggested to induce depassivation of these passive films under the same conditions. Here we use DFT+U to investigate the mechanism of the depassivation by studying the interactions of OH and Cl with the pristine and defective α-Fe2O3 (0001) surfaces and hematite (α-Fe2O3) is used to represent the Fe (III) oxides. On the pristine surface, the adsorption of both adsorbates can affect mostly the positions of the top two layers. The structural change increases with coverage and calculation of low coverages shows that the effects are localized. The largest effects on the surface were caused by the OH at high coverage and co-adsorption of OH and Cl, which suggests that OH could play an important role in the Cl-induced depassivation process. On the defective surfaces, Fe vacancy surface and O vacancy surface are studied. On Fe vacancy surface, Fe top site is the most stable site for both adsorbates, and the adsorption energy for the two adsorbates and structural effects caused by the adsorption are comparable to those on the pristine surface. The insertion of one Cl into the second layer of α-Fe2O3 is endothermic, with the reaction energy about 0.7 eV, which suggest that Cl is thermodynamically favorable to adsorb on the surface. Similarly on O vacancy surface, Cl is more stable on the Fe top site closer to the vacancy than in the O vacancy suggesting that the vacancy affects the Cl adsorption indirectly.
In Situ X-Ray Absorption Spectroscopy Investigation of Silver-Copper Nanoparticles for the Oxygen Reduction Reaction
Authors: Gibbons Brenna M. , Higgins Drew Christopher , Wette Melissa , Mehta Apurva , Davis Ryan C. , Clemens Bruce M. , Jaramillo Thomas F
Published: February 2020

The electrochemical conversion between oxygen and water is a key process gating the wider deployment of a variety of renewable energy technologies. In particular, the slow kinetics and limited selection of suitable catalysts for the oxygen reduction reaction (ORR) are main impediments to the expansion of critical clean-energy technologies such as hydrogen fuel-cell vehicles or grid-scale energy storage. While Pt-based catalysts are the conventional choice for acidic electrolytes, favorable oxygen reduction kinetics and stability considerations that occur in alkaline electrolytes provide possibility for using non-platinum group metal catalysts, including silver. In particular, bimetallic or alloyed systems of silver and copper have been predicted by theory to be active for the ORR [1]. While these two metals have a large miscibility gap in the bulk, it has been shown that small nanoparticles can support intermixing of the silver and copper in a stable or metastable phase [2]. In addition, we have shown that co-sputtering silver and copper as both thin films and nanoparticles results in ORR catalytic activity that surpasses that of either metal on its own. In this work we investigate these bimetallic catalysts using in situ x-ray absorption spectroscopy (XAS) in order to help understand the activity enhancements seen when combining copper and silver for the ORR.

[1] K. Shin, D.H. Kim, and H.M. Lee. ChemSusChem (2013), 6: 1044-1049.

[2] P. Grammatikopoulos, J. Kioseoglou, A. Galea, J. Vernieres, M. Benelmekki, R.E. Diaz, and M. Sowwan. Nanoscale (2016), 8: 9780-9790.
(Invited) Investigating the Water-Stimulated Mg2+ Insertion Mechanism in an Electrodeposited MnO2 Cathode
Authors: Sahadeo Emily , Song Jaehee , Gaskell Karen J. , Rubloff Gary W , Lee Sang Bok
Published: February 2020

Magnesium batteries are an important energy storage technology being investigated to improve upon, and move beyond, current lithium-ion (Li-ion) battery systems. Some advantages of magnesium-based batteries include magnesium’s abundance, increased volumetric capacity, and lower reactivity compared to Li. However, Mg batteries have many challenging problems hindering their implementation. One major issue is the slow intercalation kinetics of the Mg2+ ion in many metal oxide cathodes conventionally used in Li-ion batteries. A potential solution that has been demonstrated is adding water molecules into organic electrolyte; this method has shown increased Mg insertion and performance of cathode materials such as vanadium oxide (V2O5) and manganese oxide (MnO2). MnO2 is the cathode of interest for this work, and an in-depth investigation is necessary to fully understand the role of the water molecules in the Mg intercalation into this material.

In this work, the Mg insertion mechanism is being investigated in a system of water-in-organic electrolyte, with electrolytes containing an H2O to Mg ratio of 6:1. The cathode is an amorphous, electrodeposited MnO2 thin film. Thin film MnO2 electrodes were prepared so that they could be electrochemically cycled in magnesium perchlorate/propylene carbonate electrolyte, and subsequently examined via ex-situ XPS at different stages of charge and discharge to monitor the surface chemical speciation and any changes. Herein, we will elucidate upon the XPS results to help explain the mechanism of Mg insertion in this mixed electrolyte. Results demonstrate that an Mg(OH)2 layer forms upon discharge, and this hydroxide layer is reversibly formed and removed during charge and discharge. Additionally, after first cycling electrodes in wet electrolyte and transferring them to dry organic electrolyte and cycling further, the Mg(OH)2 layer is still observed although in a diminished capacity.

We propose that in the mixed water-in-electrolyte system, there is a combined insertion/conversion reaction mechanism whereby an Mg(OH)2 layer is formed on the surface. We therefore believe water inserted into the MnO2 structure upon cycling in wet electrolyte may be responsible for the Mg(OH)2 formation in dry electrolyte and continual increased Mg-ion capacity. A more complete understanding of the mechanism for this phenomenon may help in further developing strategies to improve metal oxide cathode performance. For instance, one possibility may be trying to reproduce the positive effect of water with another additive that does not react with the Mg anode as water does.
Cobalt Complexes As Single Redox Molecules for Catholyte and Anolyte in Redox Batteries
Authors: Nikiforidis Georgios , Yang Chunzhen , Luo Yong , Hou Zhaomin , Byon Hye Ryung
Published: February 2020

We herein present the design and realization of chelating ligands in modulating redox potentials of the central metal ion, offering a single redox molecule to both catholyte and anolyte applicable in the field of redox batteries. We demonstrated an increase in redox potentials from the bidentate and tridentate ligands that are coordinated with Co(II) forming pseudo-octahedral complexes. The cyclic voltammetry (CV) curves using a three-electrode cell show quasi-reversible behavior of the Co(I/II) and Co(II/III) redox couples in non-aqueous electrolyte solutions such as carbonate and glymes. Further, the potential of Co(II/III) is altered due to the electron deficiency of ligands. Amongst the ligands investigated, tridentate and the most electron deficient one provide the highest peak to peak voltage, equal to ~1.85 V. The single species of Co complex in the redox cells with 200 mM delivers ~22.3 mAh L-1 and ~98% capacity retention for 300 cycles at a current density of 0.2 mA cm-2 and 35ºC (Fig.1), yielding a volumetric energy density of 40.7 Wh L-1. At a current density of 0.5 mA cm-2 Coulombic efficiency lingers at ~96% over 600 cycles, demonstrating a promising redox cell with long-term cycling stability. The ligand design associated redox-reaction process and the stability of Co complex for galvanostatic cycling would be further discussed in the presentation.

Figure 1
Fabrication of Shaped Controlled Cerium Oxide Nanomaterial for Highly Sensitive Enzymatic Glucose Biosensors
Authors: Fallatah Ahmad Mohammadhabeeb , Almomtan Mohammed , Padalkar Sonal
Published: February 2020

Metal oxide semiconductors at the nanometric scale have attracted considerable attention in recent years. Cerium oxide (CeO2) is one such metal oxide semiconductor that has received significant attention due to its catalytic and free radical scavenging properties and finds applications in medicine, catalysis and sensing. Here CeO2 was prepared by electrodeposition technique on a fluorine doped tin oxide (FTO) substrate. For electrodeposition, cerium nitrate and dimethyl sulfoxide (DMSO) were used. Several CeO2 samples were prepared with varying amount of DMSO. The current density and temperature of deposition was 2 mA/cm² and 70°C respectively. The fabricated CeO2 samples were characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and UV-visible spectroscopy. Additionally, the CeO2 samples were tested for glucose sensing. The enzymatic glucose biosensor was prepared by immobilizing glucose oxidase (GOx) enzyme on the CeO2 samples. The amperometric current response of the glucose biosensor was recorded at every addition of glucose. Furthermore, electrochemical impedance spectroscopic (EIS) method was used to study the charge transfer in the fabricated biosensors. Finally, a comparison of different CeO2 biosensors was carried out.
A Paper-Based Surface-Enhanced Raman Scattering Test Strip for Protein Biomarker Detection
Authors: Gao Xuefei , Zheng Peng , Kasani Sujan , Wu Nianqiang
Published: February 2020

Paper-based lateral flow strips (PLFS) have received increasing attention as point-of-care (POC) tools due to their low cost and simplicity to use. However, PLFS usually suffer from poor sensitivity and serious interference from their sample matrix when they are used with blood plasma containing samples. In our current study, surface-enhanced Raman scattering (SERS) was integrated as the signal transducer into PLFS for protein biomarker detection in blood plasma. Compared with the traditional colorimetric PLFS, the SERS PLFS exhibits advantages in terms of sensitivity and limit of detection (LOD) in a blood plasma sample matrix. These advantages are attributed to the wavelengths of both the excitation light and the Raman scattering signals being able to be tuned into the near-infrared biological window. Herein, our developed SERS PLFS has been successfully demonstrated for detection of neuron-specific enolase (NSE) in diluted blood plasma samples with a LOD of 1 ng/ml. Moreover, these SERS based test strips are in expensive, fast (30 min) and simple to be operated, holding a great potential in assisting screening of traumatic brain injury (TBI) patients in a point-of-care setting.
Preparation and Characterization of Electrochemical Tyrosinase Biosensor
Authors: Polatoglu Ilker
Published: February 2020

Tyrosinase enzyme is a binuclear copper cluster containing monooxygenase contains a dicopper core in the active site [1]. This enzyme catalyzes the o-hydroxylation of monophenols and subsequent oxidation of the formed o-diphenols into the o-quinones. Depending on the electrochemical reduction of o-quinone, amperometric detection of phenol which is a high toxic compound can be achieved. For this aim spectrophotometric and chromatographic methods have been commonly used. Due to their lots of disadvantages, electrochemical enzyme sensors become promising alternative [2]. The performance of enzyme sensors strongly depends on the immobilization of the enzyme to the appropriate support. Many significant biological and chemical properties of chitosan attract attention as a potential support for enzyme immobilization [3]

In current study, tyrosinase enzyme was immobilized on chitosan support enhanced by magnetite nanoparticles. Electrochemical biosensor was constructed by coating this bionanocomposite film on 5mm diameter of working electrode. All electrochemical measurements were performed with a model PGSTAT 128N (AUTOLAB Instruments) having three electrode system (working electrode: tyrosinase–magnetite-chitosan modified glassy carbon, reference electrode: Ag/AgCl, auxiliary electrode: platinum wire). The interaction between the sensor component and their structure were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Electrochemical characterizations were also performed by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The performance of electrochemical tyrosinase biosensor was tested by amperometric method in magnetically stirred PBS, followed by the addition of catechol solution as a phenolic compound.

The binding of tyrosinase enzyme to the bionanocomposite support was confirmed by FTIR and SEM analysis. According to the CV measurements, the reduction peak was observed attributed to the direct reduction of quinone on the electrode surface. EIS results showed decrease in mass transfer resistance indicate conducting properties of magnetite nanoparticles. Electrochemical sensing characteristics and analytical performance of developed sensor was also evaluated by amperometric detection of catechol. The designed sensor depicted wide linear range of catechol concentration with high correlation coefficient, high sensitivity, low detection limit and Kmvalue.

Acknowledgements

This study was supported financially by the Scientific and Technological Research Council of Turkey (TUBITAK Grant Number 114Z417).

 

References

[1] Abdullah J, Ahmad M, Karuppiah N, Henga LY, Sidek H, Sensors and Actuators B, 114 (2006) 604-609.

[2] Li GY, Jiang Y, Huang K, Ding P, Chen J, Journal of Alloys and Compounds, 466 (2008) 451–456

[3] Krajewska B, Enzyme and Microbial Technology, 35 (2004) 126–139
Enhanced Protein Stability Using Room Temperature Ionic Liquid for Wearable Electrochemical Sweat-Based Biosensor
Authors: Jagannath Badrinath , Muthukumar Sriram , Munje Rujuta D. , Prasad Shalini
Published: February 2020

In this abstract we demonstrate the implementation of a hybrid aqueous/room temperature ionic liquid (RTIL) interface towards the development of a wearable biosensor for detection of inflammation through the use of a diagnostics protein biomarker. RTILs have low vapor pressure and a wide electrochemical window. RTILs are also known to stabilize proteins based on their physical properties such as hydrophobicity or hydrophilicity, viscosity and the chemical interaction of the RTIL with various functional groups of a protein. Typically, proteins are stable in RTILs with chaotropic cation and kosmotropic anion. Also, the interaction of anionic moiety with protein influences the protein stability as compared to the cationic moiety. We leverage the physicochemical properties of the RTIL, BMIM[BF4], along with its excellent electrochemical properties towards the development of a wearable electrochemical biosensor for the detection of IL-6 in human sweat. Firstly, the stability of α IL-6 antibody in RTIL was evaluated using optical techniques such as ATR-FTIR, dynamic light scattering (DLS) to determine any conformational changes or aggregation of the protein. ATR-FTIR temporal studies showed that the antibody was more stable in BMIM[BF4] (up to 96h) without any peak shifts as compared to PBS (up to 48h) and no aggregation in protein size was observed using DLS for up to 96h in BMIM[BF4]. Further, high zeta potential values for volumetric ratios ≥50% BMIM[BF4] in synthetic sweat(pH 2- 8) indicate that the protein does not aggregate in the presence of BMIM[BF4]. Once the enhanced stability of protein in BMIM[BF4] was confirmed, non-faradaic electrochemical impedance spectroscopy (EIS) was performed to assess the sensor performance metrics for detection of interleukin -6 (IL-6) in human sweat. The wearable sensor with metal-semiconductor electrode functionalized with IL-6 antibody in RTIL showed a limit of detection of 0.2pg/mL up to 24h, 2 pg/mL between 24- 48h, 5pg/mL between 48- 96h post-antibody functionalization. This LOD is below the physiological relevant range of 7-16 pg/mL. The linear dynamic range of the sensor obtained was 0.2- 200 pg/mL. This enhanced sensor performance is not only due to the protein stability maintained by the RTIL but also because of the electrochemical characteristics of RTIL that contributed to the enhanced electrical double layer post 96h immobilization. The physical, electrochemical along with protein stabilization properties of RTIL make it novel for electrochemical protein biosensing.
Magnesium-Ion Batteries Based on Tin-Based Anode Material
Authors: Nguyen Dan Thien , Song Seung-Wan
Published: February 2020

Rechargeable magnesium batteries have received a considerable attention as one of the beyond-lithium batteries for next-generation energy storage systems. Magnesium is earth abundant and low cost compared to lithium, and has higher theoretical volumetric capacity (3833 mAhcm-3) than lithium. The use of magnesium metal anode is often limited due to the irreversible formation of surface blocking layer in conventional electrolytes and the limited choice of counterpart cathode material in Grignard reagent-based electrolytes. Recently, insertion-type materials such as Bi, Sn, Sb, etc., which is based on the alloy reaction with magnesium, have been proposed as a new class of alternative anode materials to magnesium metal. Obtaining a good charge-discharge cycling performance of those new materials is however a challenge. We have been pursuing the development and application of tin-based anode materials, which enables magnesium-ion batteries. Herein, we report our recent research results of the electrochemical performance and interfacial phenomena of tin-based anode materials.

This work was supported by National Research Foundation of Korea (2015062107).
On the Stability of Interphases in Na Batteries
Authors: Ponrouch Alexandre , Dugas Romain , Iermakova Daria , Palacin M Rosa
Published: February 2020

Lithium metal anodes are widely used as counter (or also reference) electrodes in the so termed half cell tests, used mostly at laboratory scale within the battery research community. These are intended to assess the electrochemical performance of a given compound as either positive or negative electrode material for Lithium ion batteries in a simple way, avoiding the assembly of full cells in which electrode balancing can severely affect performance.

The reliability of extrapolating such half cell testing results to potential performance in full cells is linked to the stability of the Solid Electrolyte Interphase (SEI) typically formed on the surface of lithium metal anodes as a result of electrolyte degradation reactions. Reliability and representativity of analogous half test cells in Sodium ion battery research has been generally taken for granted.

In this context, the aim of our work was to perform a comparative study of the composition, morphology and stability of the SEI formed on lithium and sodium with state-of-the art electrolytes. The impact of the use of Li or Na counterelectrodes in half cell configuration when testing hard carbon electrodes was also investigated. Our results clearly point at the existence of significant differences which cast some doubts on the representativity of half-cell tests and call to exercise care in the extrapolation of their results.1,2

Figure 1. Charge/discharge curves of symmetric Li/Li (red curve) and Na/Na (blue curve) cells cycled at 0.05 mA/cm2 (25˚C) and using 1 M LiPF6 or NaPF6 in EC0.5DMC0.5. Poorer cyclability was observed for Na cells when compared with Li cells.

References:

1. D. Iermakova, R. Dugas, M.R. Palacín, A. Ponrouch, J. Electrochem. Soc., 162 (2015) A7060.

2. R. Dugas, A. Ponrouch, G. Gachot, R. David, M.R. Palacín, J.M. Tarascon, J. Electrochem. Soc., 163 (2016) A1.

Figure 1
Computational and Spectroscopic Analysis of Ion Interactions in Sodium and Lithium Ion Battery Electrolytes
Authors: Cresce Arthur v. , Borodin Oleg , Greenbaum Steven , Peng Jing , Gobet Mallory , Rogers Reginald , Xu Kang
Published: February 2020

Rising interests in sodium ion batteries as low-cost alternatives to lithium ion batteries necessitates a closer look at the interactions between the sodium ion and its anion in electrolyte solution. As demonstrated in lithium ion batteries, solvent and anion species involved in solvation of the lithium ion contribute to the nucleation and growth of the solid electrolyte interphase of the anode. The same is true of sodium ion batteries, which parallel lithium ion batteries in their use of carbonate-based organic solvents and the hexafluorophosphate (PF6
-) anion. Infrared spectroscopy (FTIR) was used to probe the interaction between PF6
- and sodium in various carbonate-based solvent, and these measurements were interpreted using predictions made by density functional theory (DFT) calculations on the model LiPF6 and NaPF6-based solvates. In addition, molecular dynamics (MD) simulations were performed on the EC:DMC/LiPF6 and EC:DMC/NaPF6 electrolytes. A revised many-body polarizable APPLE&P force field was used in MD simulations. Solvate structures extracted from MD simulations were found in good agreement with interpretations of FTIR spectra. Specifically, initial MD results supported our previous finding indicating that the Li+ and Na+ solvation numbers from Raman measurements are found are similar in linear carbonates. Moreover, MD simulations predicted that the PF6
- anion coordination to Li+ and Na+ are quite different. Mono-dentate LiPF6 binding prevailing in LiPF6-DMC, and a combination of bi- and tri-dentate binding dominating in NaPF6-DMC in agreement with the free energies of solvates estimated from DFT cluster – continuum calculations. MD simulations also predicted solvent, anion, Li and Na self-diffusion coefficients in excellent agreement with pfg-NMR measurements.
Predicting Lithium Polysulfide Solubility and Reaction Pathway Using a Unique Donicity Scale for Li-S Electrolytes
Authors: Watkins Tylan S , Zavadil Kevin R
Published: February 2020

Sparingly Solvating Electrolytes for Li-S Cells:

Use of electrolytes with low lithium polysulfide (Li2Sn) solubility limits has attracted considerable interest in recent literature.1 This “sparingly solvating” strategy has been adopted by some as a means for significantly reducing redox shuttling of Li2Sn between the cathode and anode. Interestingly, some sparingly solvating electrolyte compositions, employing significantly high concentrations of LiTFSI, have not only shown promising cycling performance, but have also shown a unique discharge voltage profile—lacking the typically observed two plateau response produced by sequential soluble long chain Li2Sn and short chain Li2Sn formation. This unique voltage profile is thought to be the result of significantly suppressed concentrations of longer chain Li2Sn (n > 4) leading to initial sulfur reduction through a solid state pathway followed by Li2Snreduction mediated by a low solubility intermediate.

Predicting Li2Sn Solubility and Reaction Pathway:

What remains to be elucidated is a more quantitative assessment for the solubility regimes in which the alternative sulfur reduction pathway occurs. Furthermore, a deeper understanding of the electrolyte characteristics that dictate Li2Sn solubility is lacking. In this talk, a unique 23Na NMR-derived donor number (DN) scale is presented, similar to that described by Schmeisser et al.2 Evaluation of donicity in this manner allows for a direct comparison between electrolytes utilizing different solvating species; see Figure 1 for THF and acetonitrile (AcN)-based electrolytes. It will be demonstrated that the 23Na-DN assignments are predictive indicators for solubility of Li2Sn (Figure 2). Finally, it will be shown that solubility can be used to predict the thermodynamic redox potentials for Li-S cells as a function of discharge capacity. Figure 3 shows representative galvanostatic intermittent titration technique (GITT) experiments performed on two different AcNxLiTFSI electrolytes, with drastically different Li2Sn solubility limits; the black traces follow the open circuit potentials at given capacities. Clearly, AcN6LiTFSI shows a classic two plateau response, in which the second plateau (later discharge) is at a lower potential than the early discharge plateau—consistent with higher Li2Sn solubility. Alternatively, AcN2LiTFSI shows a mid-discharge plateau higher than that of the potential at early discharge—consistent with a mechanism driven by a lack of solution phase Li2Sn (n > 4) species. Further details describing how these voltage profiles change as a function of Li2Snsolubility will be provided.

References:

Cheng, L.; Curtiss, L. A.; Zavadil, K. R.; Gewirth, A. A.; Shao, Y.; Gallagher, K. G. ACS Energy Lett. 2016, 1, 503−509.

Schmeisser, M.; Illner, P.; Puchta, R.; Zahl, A.; Eldik, R. Chem. Eur. J. 2012, 18, 10969–10982.­­

Figure 1
A Sodium Hybrid Capacitor with High Energy Retention and Ultra-High Stability
Authors: Thangavel Ranjith , Kim So Young , Gong Ming Kyung , Park Joo Yeon , Ramasamy Hari Vignesh , Lee Yun Sung
Published: February 2020

Sodium ion batteries have been recently proved to be a cost-effective and promising alternative to lithium-ion batteries for next generation high-energy applications. However, the sluggish intercalation kinetics in batteries greatly forbid the efficient high power operation.[1] Recently, sodium hybrid capacitors (NHCs) emerged as a promising energy storage system to retain high specific energy at high power conditions. Benefiting from the simultaneous sodium intercalation/deintercalation in battery type electrode and anionic adsorption/desorption in capacitor type electrode, a fast kinetics in NHCs have been achieved.

However, the poor sodium ion storage in battery electrode along with limited anionic adsorption in commercial electrode diminish the output performance of NHCs. The research on NHCs is still in a nascent stage and requires deep investigation to improve energy retention and cycle stability at high power. The kinetics in both battery and capacitor type electrodes must be synergistically improved to achieve a high energy.[2] In this work, we developed a high performing NHC with metal oxide nanoparticles embedded in graphene network as a battery electrode along with a highly mesoporous carbon derived from bio-mass precursor as a capacitor electrode. The highly favorable architecture in both the electrodes showed an enhanced capability towards ion storage (Shown in Ragone plot). A high energy retention at high power condition along with ultra-high stability have been achieved. The detailed results will be presented and discussed in detail.

References

[1] J. R. Miller, P. Simon, Science
2008, 321, 651.

[2] R. Thangavel, B. Moorthy, D. K. Kim, Y.-S. Lee, Adv. Energy Mater.
2017, 1602654.

Figure 1
Synthesis and Characterization of V2-X
Mo
x
O5 Cathode Materials for Calcium Ion Batteries
Authors: Sakurai Yoji , Minami Ryoji , Murata Yoshiaki , Takada Syoki , Tojo Tomohiro , Inada Ryoji
Published: February 2020

Recently, a great deal of attention has been paid to multivalent ion batteries as post lithium ion batteries (LIBs) [1]. Among them, calcium ion batteries (CIBs) could exhibit a high cell voltage and energy density due to the low standard electrode potential of Ca/Ca2+, -2.87 V vs. NHE, which is comparable to that of Li/Li+ (-3.05V vs. NHE). In addition, CIBs have attractive advantages such as the higher safety and lower cost compared with LIBs. However, there are only a few reports in which electrodes for CIBs show a reversible calcium ion insertion/extraction. Almost a decade ago, we found that some vanadium oxides, e.g. crystalline V2O5 with layer structure, undergo reversible reaction with Ca2+[2,3].

However, a V2O5 cathode exhibits the large overvoltage as well as the poor rate performances due to its low electronic conductivity. In this study, we studied the effect of substituting Mo6+ for a part of V5+ in V2O5 in order to improve the electronic conductivity of V2O5. The carrier electrons are expected to be generated by the substitution of Mo in terms of the so-called valence control expressed as V5+/V4+. We synthesized a series of Mo-substituted V2O5, i.e. V2-x
Mo
x
O5 (x=0.02, 0.06, 0.1), by solid state reaction, and evaluated their electrochemical properties in comparison with a parent V2O5.

XRD patterns of the synthesized V2-x
Mo
x
O5 (x=0.02, 0.06, 0.1) powder all exhibited main diffraction peaks similar to those of V2O5 without impurity phases, indicating the solid solution formation. In addition, XPS measurements of V2p and Mo3d orbital showed main peaks attributed to V4+ and Mo6+ by Mo substitution in V2O5. Therefore, the V sites in V2O5 were suggested to be partially substituted to Mo. Galvanostatic cycling in LIBs revealed that a V1.94Mo0.06O5 electrode showed the lowest overvoltage than that of other compositions. Therefore, we focused on V1.94Mo0.06O5 in order to evaluate electrochemical characteristics for CIBs. The V1.94Mo0.06O5 cathode evaluated in CIBs showed reversible discharge and charge profiles with less overvoltage as well as the improvement in cycle performance compared to V2O5. XRD and EDX analyses also supported the reversible insertion/extraction reaction of V1.94Mo0.06O5 with Ca2+ ions. Therefore, it is suggested that V1.94Mo0.06O5is feasible as one of cathode materials for CIBs.

References

[1] J. Muldoon, C.B. Bucur and T. Gregory, Chem. Rev., 114 (2014) 11683.

[2] M. Hayashi, H. Arai, H. Ohtsuka and Y. Sakurai, J. Power Sources, 119-121 (2003) 617.

[3] M. Hayashi, H. Arai, H. Ohtsuka and Y. Sakurai, Electrochem. Solid-State Lett., 7 (2004) A119.