Nanoscience 2017

Improving titanium dioxide nanoparticle suspension for aquatic toxicity studies of endocrine disruptors |  Courtney J. Kristoff, Marriah C. G. Ellington and Lisa A. Holland 

C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, WV 26506 

Approximately 38,000 tons of titanium dioxide nanoparticles (nTiO2) are disposed of in the water systems each year, but the health effects of them are unknown. These nanoparticles have demonstrated endocrine-disruption in laboratory studies; however, different methods of dosing were used because nTiO2 is difficult to suspend and deliver in aquatic systems. A standard protocol is necessary in order to ensure consistency across aquatic toxicity studies. The Organization for Economic Cooperation and Development provides guidelines for aquatic toxicity studies that state the concentration of test substance throughout the 21-day study must remain within ±20% of the initial concentration. However, no effective procedure has been developed for maintaining that concentration when using insoluble materials. The focus of this research is developing the most effective method for suspending nTiO2 in solution. Titanium dioxide nanoparticles were suspended in solution and samples were collected over a 12-hour period to be analyzed via inductively coupled plasma optical emission spectroscopy. Once developed, the method is applied to a 21-day aquatic toxicity study to analyze the endocrine-disrupting health effects of nTiO2 in zebrafish. 

Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 and Joint Quantum Institute, Department of Physics, University of Maryland & NIST 

Due to their potential to generate single indistinguishable photons, quantum dots are prime candidates for the development of quantum bits, or qubits, for quantum computation protocols. In theory, photon emission requires only the excitation of the quantum dot from a laser that is resonant with the system. In practice, due to charge relaxation processes with the semiconductor host, a second higher-energy laser is required to also excite the system in order to produce a photon. If quantum dots are ever to be used as qubits, these charge relaxation processes must be fully characterized. By modulating this higher-energy laser while keeping the resonant laser on, we have measured the time dependence of the fluorescence emitted by the quantum dot. We are developing physical models that will be used to fit this data. These models focus on the charge populations within the quantum dot as well as in external reservoirs. We expect our results to confirm there exists some external reservoir, possibly a defect, heavily influencing the charge dynamics of the quantum dot. 

Toxicity of inhaled welding fumes on exposed worker respiratory and reproductive cell lines |  Karagan A. Mulhall1, Anna M. Morris1, Nicole S. Olgun1 and Stephen S. Leonard1,2 

Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, 26505 and Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, WV 26506 

The U.S. Department of Labor Women’s Bureau says that the number of female welders in the United States is approximately 26,000 and has increased by more than 2% over the past decade. This work causes welders to inhale fumes produced by the metal rods. Our study uses mouse monocyte macrophages (RAW 264.7) and human placental cells (HTR8) to investigate the possible toxicity of stainless steel (SS) and mild steel (MS) welding fumes on respiratory and reproductive systems. Welding fumes were collected and sized to determine their chemical characteristics and ability to penetrate biological systems. The possible toxic effects of both types of fume were measured using cell viability, generation of reactive oxygen species (ROS), cell membrane damage, DNA damage, and cytokine release. Fumes were found to contain different chemical make-up and a mean size of 166.2 nm. ROS showed an increase after exposure with SS fumes being significantly higher. Both DNA damage and cytokine production showed increases after exposure. SS showed increase in toxicity when compared to MS in both RAW 264.7 and HTR8. 

Optimizing the treatment of substrates for high quality growth for magnetic materials 

Allison Haertter, Navid Mottaghi, Shalini Kumari, Saeed Yousefisarraf and Mikel Holcomb 
Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506-6045 

Many current and future devices rely on the use of magnetic materials, such as non-volatile computer memory, energy generation, and sensing. However, sometimes magnetic materials lose their magnetic properties, especially when thickness is decreased, which greatly impacts the performance of the device. At this time, the quality of the substrate can influence the magnetic properties it possesses, but the cause of this lost magnetism is unknown. The goal of this project is to finalize a recipe of ideal cleaning and annealing for the production of consistent, high quality substrates. This was done by adjusting different aspects of the substrate treatment such as: elements used for cleaning, annealing time, annealing temperature, the type of furnace used in annealing, and the substrate placement within the furnace. The surface quality of the single-terminated, flat substrate is determined through atomic force microscopy. After magnetic measurements, the quality of the substrate was found not have a major effect on the loss of magnetism, it is instead due to some aspect of the thin film which is now being explored. 

Immobilization platform for the next generation of efficient enzyme-based systems with industrial applications |  K. C. Williams, Q. Liu, C. Z. Dinu 

Department of Chemical and Biomedical Engineering, West Virginia University, Morgantown, 26506 

Carbonic anhydrase (CA) accelerates the conversion of CO2 into carbonates by one million molecules per second. Under industrial conditions in CO2 capture and sequestration, this rate is substantially reduced. We use a combinatorial approach employing both computational and experimental designs to evaluate strategies maximizing enzyme functionality for industrial sustainability. The enzymes soybean peroxidase (SBP), a model enzyme and carbonic anhydrase (CA), the enzyme of interest, were rendered in 3D using SwissPDB software, determining active sites allowing predictions to be made relevant to binding to nanosupports. Bicinchoninic acid (BCA) assay was performed to determine bound enzyme concentration, and enzyme specific activity assays were performed to both free and bound enzymes to measure changes in kinetic activity. Experimental analysis showed that changes in enzyme kinetics are function of the nanosupport and method used for immobilization. Computational analysis showed that these changes are due to enzyme-nanosupport interactions can be predicted based on enzyme surface properties. Our results suggest that industrial applications of CA could become feasible if ensure user-controlled immobilization techniques utilizing computational predictions are implemented. 

Determining the relationship between the functionalization of carbon nanotubes and their toxicity |  Sarah L. Hejnosz, Tyler A. Davis, Jenny L. Bundy, David T. Lowry, Lisa A. Holland and  Linda M. Sargent 

1 C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506 and 2 National Institute for Occupational Safety and Health, Morgantown West Virginia, 26505 

Carbon nanotubes have a high presence in the manufacturing industry and their toxicity is still not well known. Carbon nanotubes can easily aerosolize and studies have shown when inhaled they have potential to cause pulmonary complications. It has been suggested that there is a reduction in toxicity when the carbon nanotubes are functionalized rather than when they are in their pristine form. The simplest functionalization method is carboxylation via acid washing. The acid washing process consists of sonicating Mitsui 7 carbon nanotubes in a concentrated sulfuric acid and nitric acid mixture for a desired amount of time. In this study, three degrees of carboxylation on Mitsui 7 carbon nanotubes were obtained and characterized via capillary electrophoresis. Once characterized an exposure study on immortalized respiratory epithelial cells was performed using a low and a high dose of the three different degrees of carboxylated Mitsui 7 carbon nanotubes and pristine Mitsui 7 carbon nanotubes. Cell viability was determined using the Alamar Blue assay. 

Manipulation of Laporte selection rules in CuAlO 2 by alloying with iron |  Jay Magers, Mina Aziziha, Pedram Tavazohi and Matthew Johnson 

Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 and Department of Physics, Susquehanna University, 514 University Avenue, Selinsgrove, PA 17870 

Complex oxides, most notably perovskite material system (A2+B4+O2−3), are multifunctional materials that are finding a wide range of photonic and electronic applications. The delafossite oxide system (A1+B3+O2-2) is a much less explored with a wide range of possible alloy combinations that may have properties leading to novel applications. By using two site-B elements, quaternary (AB1B2O2) alloys result. Not only does this increase the possible material combinations; it can introduce strain into the crystal, breaking the symmetry, and allowing optical selection rules (Laporte selection rule) to be bypassed. In this study, we explore the quaternary alloy, CuAl1-xFexO2, with x=0.0 to 0.1. Powder samples are synthesized by solid-state reaction of mixtures of Fe2O3, Cu2O and Al2O3 in a furnace at ~1,100oC. Using x-ray diffraction, for x=0.1, we found the changes in the in-plane ( a) lattice parameter increases by 0.55%, while the out-plane ( c) lattice parameter increases by only 0.08%. UV-Vis spectroscopy measurements show both the direct and indirect optical band gaps shift to higher values, as the concentration of iron within the quaternary alloy increases. 

Measuring AC Stark shifts of quantum dot energy levels |  Kimberly Matsinger, Tristan Wilkinson, Disheng Chen and Edward Flagg 

Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 

A confined electron spin within a quantum dot (QD) is a potential candidate to act as a quantum bit. Currently there is no method that allows for initialization, manipulation, and readout of the electron spin, all of which are necessary for a qubit. The driving hypothesis is that the AC Stark effect will allow for spin preserving cycling transitions, which can be used for single-shot spin measurements. The first objective is to demonstrate the AC Stark effect on QD energy levels, which can be studied and characterized via excitation spectroscopy. The preliminary results show that the AC Stark shift cannot be measured on neutral quantum dots without independent charge control. When the AC Stark laser is applied, the QD energy levels shift due to a change in the charge environment of the quantum dot that is not related to an AC Stark shift. 

Development of a plasmon-enhanced near-infrared fluorescent nanoprobe for detection of cancer biomarkers |  Ashley E. Boryczka, Peng Zheng and Nianqiang Wu 

Department of Mechanical and Aerospace Engineering,
West Virginia University,  Morgantown, WV 26506 

Around 40% of world populations are diagnosed with cancer in a lifetime according to World Health Organization. Cancer is one of the leading causes of death, accounting for nearly one in six deaths worldwide. As an effective treatment of cancer proves highly challenging, the best practice of fighting cancer lies at early diagnosis. However, it remains a great challenge since the level of cancer biomarkers is very low at early stages. To address this issue, we have developed a plasmon-enhanced near-infrared fluorescent nanoprobe, consisting of a gold nanostar at the core, a silica shell, and near infrared (NIR) quantum dots (QDs), forming an Au nanostar@SiO2@QDs nanoparticle. This nano-probe has several advantages. First, the nature of NIR fluorescence helps minimize background noise and maximize the penetration depth in biological samples. Second, the strong plasmonic field of Au nanostars helps improve the intrinsically weak fluorescence emission of NIR QDs dramatically, allowing a highly sensitivity. Third, the silica shell makes the nano-probe water-soluble. The nanoprobe obtained has a great potential application in early detection of cancers, especially in the precancerous stages, potentially saving many lives. 

Nanoparticle nucleation via atomic force microscopy |  Landon Hall, Andrew Graves and Charter Stinespring 

Benjamin M. Statler College of Engineering and Mineral Resources,
West Virginia University, Morgantown, WV 26506 

Photodetectors have a wide assortment of uses, and with the highly tunable graphene nanoparticle composite photodetectors one can detect very specific wave lengths of light. This has applications for monitoring crop health and atmospheric mapping. These detector structures are typically created via e-beam lithography. This is a very time consuming and expensive process. A possible way to speed up this process is to “print” these structures using an atomic force microscopy (AFM) apparatus. By scanning the AFM in a liquid cell filled with a silver salt solution and applying a bias voltage between the tip and graphene surface, it is thought that the nucleation of silver particles will occur on the surface. These studies explore the feasibility of this process and investigate the effects of key parameters. These parameters include the distance between the tip and surface, concentration of the silver salt solution and scan rate of the AFM. 

Simulation of plasmonic contact enhanced light emitting diodes |  Merrik M. Malin, Casey Norville, Kyle Smith and Jeremy Dawson 

Department of Physics and Engineering, West Virginia Wesleyan College, Buckhannon, WV 26201 and Lane Department of Computer Science and Electrical Engineering West Virginia University, Morgantown, WV 26506 

The use of light-emitting diodes (LEDs) offer improved energy-savings in many lighting applications. LEDs have gathered interest due to their low power consumption, and also because they can be engineered to tune their emission wavelengths to lie within the infrared, visible, or ultraviolet spectra. Despite the high levels of internal quantum efficiency (QE) achievable in LEDs, methods of enhancing external QE are being explored. One mechanism utilized for improving the external QE is the use of nano-patterned metal contacts. When the plasma frequency of a metal couples with the LED’s emission wavelength, it can couple with surface plasmon polaritons creating a localized region of enhanced electric field density. If this high- intensity field is located in the vicinity of the multiple quantum wells (MQWs) of an LED, it will increase the emission rate of the MQWs via the Purcell effect. This work explores the FDTD simulation of enhanced emission (465nm) for a gallium nitride LED coated with a periodic plasmonic array of silver-filled nanoholes with the goal of further improving the internal QE of the LED. 

Harvesting waste heat for thermoelectric generation through addition of gold nanoparticles in oxide ceramics |  James Penney, Xueyan Song, Cullen Boyle and Cesar-Octavio Romo-De-La-Cruz 

Department of Mechanical & Aerospace Engineering at Benjamin M. Statler College of Engineering and Mineral Resources, West Virginia University, Morgantown, WV 26505 

Thermoelectric generation is the process of converting heat directly into electricity through the Seebeck Effect. The Seebeck Effect occurs when two dissimilar conductive materials create a voltage difference from a temperature difference between them. This can be used to recycle energy from a multitude of areas such as the industrial sector and automobiles. The solution comes from complex metal oxide-based thermoelectrics that are stable in air and at high temperatures. The efficiency of these materials needs to be improved and is measured by their electrical properties, needing to be increased, and thermal properties, needing to be decreased. The goal is that the gold nanoparticles will reduce thermal conductivity by increasing phonon scattering while not affecting electrical properties. Samples of an un-doped material, Bismuth doped material, and these same materials doped with gold nanoparticles at different concentrations will be tested for electrical and thermal properties to be compared. Thus far, the addition of gold nanoparticles at concentrations of 0.5%, 1.0%, and 1.5% weight have slightly improved the electrical properties.