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Physical Chemistry

2018

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Articles 1 - 25 of 25

Full-Text Articles in Physics

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger Dec 2018

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger

UNLV Theses, Dissertations, Professional Papers, and Capstones

X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate that ...


Hedgehog Spin-Vortex Crystal Antiferromagnetic Quantum Criticality In Cak (Fe1−Xnix)4 As4 Revealed By Nmr, Qingping Ding, William R. Meier, J. Cui, Mingyu Xu, A. E. Böhmer, Sergey L. Bud’Ko, Paul C. Canfield, Yuji Furukawa Sep 2018

Hedgehog Spin-Vortex Crystal Antiferromagnetic Quantum Criticality In Cak (Fe1−Xnix)4 As4 Revealed By Nmr, Qingping Ding, William R. Meier, J. Cui, Mingyu Xu, A. E. Böhmer, Sergey L. Bud’Ko, Paul C. Canfield, Yuji Furukawa

Ames Laboratory Accepted Manuscripts

Two ordering states, antiferromagnetism and nematicity, have been observed in most iron-based superconductors (SCs). In contrast to those SCs, the newly discovered SC CaK(Fe1−xNix)4As4exhibits an antiferromagnetic (AFM) state, called hedgehog spin-vortex crystal (SVC) structure, without nematic order, providing the opportunity for the investigation into the relationship between spin fluctuations and SC without any effects of nematic fluctuations. Our 75As nuclear magnetic resonance studies on CaK(Fe1−xNix)4As4 (0≤x≤0.049) revealed that CaKFe4As4 is located close to a hidden hedgehog SVC AFM quantum-critical point (QCP). The magnetic QCP without nematicity in CaK(Fe1−xNix)4As4 ...


Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott Aug 2018

Instrumentation For Cryogenic Dynamic Nuclear Polarization And Electron Decoupling In Rotating Solids, Faith Joellen Scott

Arts & Sciences Electronic Theses and Dissertations

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) using the higher polarization of electron radical spins compared to nuclear spins. The addition of electron radicals for DNP to the sample can cause hyperfine broadening, which decreases the resolution of the NMR resonances due to hyperfine interactions between electron and nuclear spins. Electron decoupling has been shown to attenuate the effects of hyperfine coupling in rotating solids. Magic angle spinning (MAS) DNP with electron decoupling requires a high electron Rabi frequency provided by a high-power microwave source such as a frequency-agile gyrotron. This dissertation describes the development ...


Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman Aug 2018

Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman

Electronic Theses and Dissertations

Aggregation of polyglutamine (polyQ)-rich polypeptides in neurons is a marker for nine neurodegenerative diseases. The molecular process responsible for the formation of polyQ fibrils is not well understood and represents a growing area of study. To enable development of treatments that could interfere with aggregation of polyQ peptides, it is crucial to understand the molecular mechanisms by which polyQ peptides aggregate into fibrils. Many experimental techniques have been employed to probe polyQ aggregation, however, observations from these studies have not lead to a unified understanding of the properties of these systems, instead yielding competing, fragmented theories of polyQ aggregation ...


Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, Alexis J. Eugene, Elizabeth A. Pillar, Agustín J. Colussi, Marcelo I. Guzman Aug 2018

Enhanced Acidity Of Acetic And Pyruvic Acids On The Surface Of Water, Alexis J. Eugene, Elizabeth A. Pillar, Agustín J. Colussi, Marcelo I. Guzman

Chemistry Faculty Publications

Understanding the acid–base behavior of carboxylic acids on aqueous interfaces is a fundamental issue in nature. Surface processes involving carboxylic acids such as acetic and pyruvic acids play roles in (1) the transport of nutrients through cell membranes, (2) the cycling of metabolites relevant to the origin of life, and (3) the photooxidative processing of biogenic and anthropogenic emissions in aerosols and atmospheric waters. Here, we report that 50% of gaseous acetic acid and pyruvic acid molecules transfer a proton to the surface of water at pH 2.8 and 1.8 units lower than their respective acidity constants ...


Infra-Red Microwave Spectra, Overtones, Degeneracy And Thermal Populations All In One Diagram, Carl W. David Aug 2018

Infra-Red Microwave Spectra, Overtones, Degeneracy And Thermal Populations All In One Diagram, Carl W. David

Chemistry Education Materials

An old drawing, which had an error in it, is re-presented (corrected) for understanding the relationships in diatomic vibrational-rotational interactions at the introductory level.


Effects Of High Pressure On Photochemical Reactivity Of Organic Molecular Materials Probed By Vibrational Spectroscopy, Jiwen Guan Jul 2018

Effects Of High Pressure On Photochemical Reactivity Of Organic Molecular Materials Probed By Vibrational Spectroscopy, Jiwen Guan

Electronic Thesis and Dissertation Repository

Chemical transformations of molecular materials induced by high pressure and light radiation exhibit novel and intriguing aspects that have attracted much attention in recent years. Particularly, under the two stimuli, entire transformations of molecular species can be realized in condensed phases without employing additional chemical constraints, e.g., the need of solvents, catalysts or radical initiators. This new synthetic approach in chemistry therefore satisfies increasing need for production methods with reduced environmental impacts. Motivated by these promises, my Ph. D thesis focuses on this state-of-the-art branch of high-pressure photochemistry. Specifically, high pressure is employed to create the necessary reaction conditions ...


Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., Demid Osipov, Daniil Moshnikov Jun 2018

Study Of The Visual Adaptation Mechanism In Marine Species With The Change Of Habitation Depth., Demid Osipov, Daniil Moshnikov

The International Student Science Fair 2018

The goal of our work was to determine the principal mechanisms that provide the difference in visual perception of two marine species that live on different depths: T. Pacificus and O. Vulgaris. In nature, visual perception of species that live deeper is shifted towards the blue region. This is related to the fact that red, orange and yellow light is absorbed more strongly by water than the blue light. On the other hand, the visual perception spectrum of an animal is determined by the absorption spectrum of the "light sensor" located in rods and cones of its eye retina. These ...


Super‐Resolution Imaging Of Amyloid Structures Over Extended Times By Using Transient Binding Of Single Thioflavin T Molecules, Kevin Spehar, Tianben Ding, Yuanzi Sun, Niraja Kedia, Jin Lu, George R. Nahass, Matthew D. Lew, Jan Bieschke Jun 2018

Super‐Resolution Imaging Of Amyloid Structures Over Extended Times By Using Transient Binding Of Single Thioflavin T Molecules, Kevin Spehar, Tianben Ding, Yuanzi Sun, Niraja Kedia, Jin Lu, George R. Nahass, Matthew D. Lew, Jan Bieschke

Electrical & Systems Engineering Publications and Presentations

Oligomeric amyloid structures are crucial therapeutic targets in Alzheimer's and other amyloid diseases. However, these oligomers are too small to be resolved by standard light microscopy. We have developed a simple and versatile tool to image amyloid structures by using thioflavin T without the need for covalent labeling or immunostaining. The dynamic binding of single dye molecules generates photon bursts that are used for fluorophore localization on a nanometer scale. Thus, photobleaching cannot degrade image quality, allowing for extended observation times. Super‐resolution transient amyloid binding microscopy promises to directly image native amyloid by using standard probes and record ...


Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu May 2018

Surface Reaction And Diffusion Kinetics In Semiconducting Metal Oxide Film Gas Sensors, Aravind Reghu

Electronic Theses and Dissertations

Chemiresistive metal oxide gas sensors based on materials such as SnO2, ZnO, and TiO2, have been investigated extensively by many researchers for a wide range of applications. The band bending model, based on the surface chemistry of highly reactive ionosorbed species (O2- or O-) and the semiconducting material properties of SnO2, TiO2 and ZnO, adequately predicts the dependence of the change in sensor conductivity (Δσ) as a function of target gas pressure and temperature. However, the band bending model is not applicable to gas sensors based on reducible oxides such as WO3, MoO3 ...


Reduction Of The Ordered Magnetic Moment And Its Relationship To Kondo Coherence In, Benjamin G. Ueland, Na Hyun Jo, Aashish Sapkota, W. Tian, Morgan W. Masters, Halyna Hodovanets, Savannah S. Downing, Connor Schmidt, Robert Mcqueeney, Sergey L. Bud’Ko, Andreas Kreyssig, Paul C. Canfield, Alan Goldman Apr 2018

Reduction Of The Ordered Magnetic Moment And Its Relationship To Kondo Coherence In, Benjamin G. Ueland, Na Hyun Jo, Aashish Sapkota, W. Tian, Morgan W. Masters, Halyna Hodovanets, Savannah S. Downing, Connor Schmidt, Robert Mcqueeney, Sergey L. Bud’Ko, Andreas Kreyssig, Paul C. Canfield, Alan Goldman

Ames Laboratory Accepted Manuscripts

The microscopic details of the suppression of antiferromagnetic order in the Kondo-lattice series Ce1-&ITx&ITLa&ITx&ITCu2Ge2 due to nonmagnetic dilution by La are revealed through neutron diffraction results for x = 0.20, 0.40, 0.75, and 0.85. Magnetic Bragg peaks are found for 0.20 <= x <= 0.75, and both the Ned temperature T-N and the ordered magnetic moment per Ce mu linearly decrease with increasing x. The reduction in mu points to strong hybridization of the increasingly diluted Ce 4f electrons, and we find a remarkable quadratic dependence of mu on the Kondo-coherence temperature. We discuss our results in terms of local-moment- versus itinerant-type magnetism and mean-field theory and show that Ce1-&ITx&ITLa&ITx&ITCu2Ge2 provides an exceptional opportunity to quantitatively study the multiple magnetic interactions in a Kondo lattice.


Hyperpolarization Of Silicon Nanoparticles With Tempo Radicals, Jingzhe Hu, Nicholas Whiting, Pratip Bhattacharya Mar 2018

Hyperpolarization Of Silicon Nanoparticles With Tempo Radicals, Jingzhe Hu, Nicholas Whiting, Pratip Bhattacharya

Nicholas Whiting

Silicon-based particles can be hyperpolarized via dynamic nuclear polarization to enhance 29Si magnetic resonance signals. Application of this technique to nanoscale silicon particles has been limited because of the low signal enhancements achieved; it is hypothesized that this is due to the low number of endogenous electronic defects inherent to the particles. We introduce a method of incorporating exogenous radicals into silicon nanoparticle suspensions in order to improve the hyperpolarization of 29Si nuclear spins to levels sufficient for in vivo MR imaging. Calibration of radical concentrations and polarization times are reported for a variety of silicon particle sizes (30−200 ...


Liquid-Like Thermal Conduction In Intercalated Layered Crystalline Solids, B. Li, H. Wang, Y. Kawakita, Q. Zhang, M. Feygenson, H. L. Yu, D. Wu, K. Ohara, T. Kikuchi, K. Shibata, T. Yamada, X. K. Ning, Y. Chen, J. Q. He, David Vaknin, R. Q. Wu, K. Nakajima, M. G. Kanatzidis Mar 2018

Liquid-Like Thermal Conduction In Intercalated Layered Crystalline Solids, B. Li, H. Wang, Y. Kawakita, Q. Zhang, M. Feygenson, H. L. Yu, D. Wu, K. Ohara, T. Kikuchi, K. Shibata, T. Yamada, X. K. Ning, Y. Chen, J. Q. He, David Vaknin, R. Q. Wu, K. Nakajima, M. G. Kanatzidis

Ames Laboratory Accepted Manuscripts

As a generic property, all substances transfer heat through microscopic collisions of constituent particles1. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations2,3. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe2. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus ...


Uncovering The Origin Of Divergence In The Csm(Cro4)2 (M = La, Pr, Nd, Sm, Eu; Am) Family Through Examination Of The Chemical Bonding In A Molecular Cluster And By Band Structure Analysis, Shane S. Galley, Alexandra A. Arico, Tsung-Han Lee, Xiaoyu Deng, Yong-Xin Yao, Joseph M. Sperling, Vanessa Proust, Julia S. Storbeck, Vladimir Dobrosavljevic, Jennifer N. Neu, Theo Siegrist, Ryan E. Baumbach, Thomas E. Albrecht-Schmitt, Nikolas Kaltsoyannis, Nicola Lanata Feb 2018

Uncovering The Origin Of Divergence In The Csm(Cro4)2 (M = La, Pr, Nd, Sm, Eu; Am) Family Through Examination Of The Chemical Bonding In A Molecular Cluster And By Band Structure Analysis, Shane S. Galley, Alexandra A. Arico, Tsung-Han Lee, Xiaoyu Deng, Yong-Xin Yao, Joseph M. Sperling, Vanessa Proust, Julia S. Storbeck, Vladimir Dobrosavljevic, Jennifer N. Neu, Theo Siegrist, Ryan E. Baumbach, Thomas E. Albrecht-Schmitt, Nikolas Kaltsoyannis, Nicola Lanata

Ames Laboratory Accepted Manuscripts

A series of f-block chromates, CsM(CrO4)(2) (M = La, Pr, Nd, Sm, Eu; Am), were prepared revealing notable differences between the Am-III derivatives and their lanthanide analogs. While all compounds form similar layered structures, the americium compound exhibits polymorphism and adopts both a structure isomorphous with the early lanthanides as well as one that possesses lower symmetry. Both polymorphs are dark red and possess band gaps that are smaller than the Ln(III) compounds. In order to probe the origin of these differences, the electronic structure of alpha-CsSm(CrO4)(2), alpha-CsEu(CrO4)(2), and alpha-CsAm(CrO4)(2) were studied ...


Investigation Of Novel Electrolytes For Use In Lithium-Ion Batteries And Direct Methanol Fuel Cells, Kartik Pilar Feb 2018

Investigation Of Novel Electrolytes For Use In Lithium-Ion Batteries And Direct Methanol Fuel Cells, Kartik Pilar

All Dissertations, Theses, and Capstone Projects

Energy storage and conversion plays a critical role in the efficient use of available energy and is crucial for the utilization of renewable energy sources. To achieve maximum efficiency of renewable energy sources, improvements to energy storage materials must be developed. In this work, novel electrolytes for secondary batteries and fuel cells have been studied using nuclear magnetic resonance and high pressure x-ray scattering techniques to form a better understanding of dynamic and structural properties of these materials. Ionic liquids have been studied due to their potential as a safer alternative to organic solvent-based electrolytes in lithium-ion batteries and composite ...


Different Topological Quantum States In Ternary Zintl Compounds: Bacax (X = Si, Ge, Sn And Pb), Lin-Lin Wang, Adam Kaminski, Paul C. Canfield, Duane D. Johnson Jan 2018

Different Topological Quantum States In Ternary Zintl Compounds: Bacax (X = Si, Ge, Sn And Pb), Lin-Lin Wang, Adam Kaminski, Paul C. Canfield, Duane D. Johnson

Ames Laboratory Accepted Manuscripts

Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms, BaCaGe and BaCaSn ...


X-Ray Spectroscopy Of Nio And Nanodiamond At Ssrl, Jackson Earl Jan 2018

X-Ray Spectroscopy Of Nio And Nanodiamond At Ssrl, Jackson Earl

STAR (STEM Teacher and Researcher) Presentations

The first aspect of this research project focuses on investigating the surface chemistry of high pressure high temperature (HPHT) nanodiamond by using X-ray spectroscopy techniques at the Stanford Synchrotron Radiation Lightsource (SSRL). HPHT nanodiamond is being examined as a biosensing tool for electric field detection based on the fluorescent nitrogen vacancy center hosted within diamond. With use of the transition edge spectrometer (TES), a state-of-the-art X-ray fluorescence detector, we are able to probe the surface and bulk properties of diamond. Preliminary work using density functional theory (DFT) has been done, offering insight into ground state energies and electronic structure. DFT ...


The Role Of Defects On The Optical, Electronic, And Magnetic Properties Of Iron-Sulfur Solids, Alyssa Ruth Landin Jan 2018

The Role Of Defects On The Optical, Electronic, And Magnetic Properties Of Iron-Sulfur Solids, Alyssa Ruth Landin

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Solids composed of iron and sulfur are earth abundant and nontoxic, and can exhibit interesting and technologically important optical, electronic, and magnetic phenomena. Troilite (hexagonal FeS) is predicted to exhibit large room temperature magnetoelectricity and may exhibit high temperature superconducting properties, and pyrite (cubic FeS2) is a promising candidate for photovoltaic

applications. However, defects naturally occur within both of these solids. Troilite contains Fe deficiencies with atomic formula Fe(1-x)S, while pyrite contains sulfur deficiencies with the atomic formula FeS(2-x). The Fe-S phase diagram is congested in these regions of slight non-stoichiometries, and even when the atomic ...


Velocity-Map Imaging Photoelectron Spectroscopy Of Small Molecular Anions, Allan Maple De Oliveira Jan 2018

Velocity-Map Imaging Photoelectron Spectroscopy Of Small Molecular Anions, Allan Maple De Oliveira

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

Gas phase anion photoelectron spectroscopy presents an opportunity for investigating molecules that are inaccessible by other experimental techniques, by providing data on the structure, reactivity and energetics of short-lived radicals and transition state species. Our recent development of a novel, plasma entrainment source of cold, weakly-bound anions opens a door to new exotic species to be investigated. In this thesis, I explore the capabilities of photoelectron spectroscopy and its application to small exotic molecular anions, while further developing and employing the novel dual-valve ion source.

The thesis begins with a brief history of photoelectron spectroscopy, followed by a description of ...


Analytical Modeling And Numerical Simulations Of Time Delays In Attosecond Streaking Of One- And Two-Photon Ionization, Cory Scott Goldsmith Jan 2018

Analytical Modeling And Numerical Simulations Of Time Delays In Attosecond Streaking Of One- And Two-Photon Ionization, Cory Scott Goldsmith

Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)

The generation of attosecond-duration (1 as = 10-18 s) coherent light through the process of high-order harmonic generation has opened the perspective for probing fundamental processes, such as photoionization, on the natural timescale of electron dynamics in matter. One probing technique is the attosecond streaking method, in which the momentum of the photoelectron is measured as a function of the time delay between the ionizing, attosecond extreme ultraviolet (XUV) pulse, and a weak, femtosecond near-infrared (NIR) pulse which streaks the momentum of the photoelectron, known as a streaking trace. The observed trace contains time information about the photoionization process in ...


Interpolymer Complexation As A Strategy For Nanoparticle Assembly And Crystallization, Srikanth Nayak, Nathan Horst, Honghu Zhang, Wenjie Wang, Surya Mallapragada, Alex Travesset, David Vaknin Jan 2018

Interpolymer Complexation As A Strategy For Nanoparticle Assembly And Crystallization, Srikanth Nayak, Nathan Horst, Honghu Zhang, Wenjie Wang, Surya Mallapragada, Alex Travesset, David Vaknin

Chemical and Biological Engineering Publications

Controlled self-assembly of nanoparticles into ordered structures is a major step in fabricating nanotechnology based devices. Here, we report on the self-assembly of high quality superlattices of nanoparticles in aqueous suspensions induced via interpolymer complexation. Using small angle X-ray scattering, we demonstrate that the NPs crystallize into superlattices of FCC symmetry, initially driven by hydrogen bonding and subsequently by van der Waals forces between the complexed coronas of hydrogen-bonded polymers. We show that the lattice constant and crystal quality can be tuned by polymer concentration, suspension pH and the length of polymer chains. Interpolymer complexation to assemble nanoparticles is scalable ...


Nonadiabatic Multielectron Dynamics In Interaction Of Molecules With Intense Laser Pulses, Andres F. Mora Jan 2018

Nonadiabatic Multielectron Dynamics In Interaction Of Molecules With Intense Laser Pulses, Andres F. Mora

Undergraduate Honors Theses

Ultrashort high intensity laser pulses have allowed for the observation of ultrafast dynamics in atoms and molecules. Due to the complexity, these multielectron systems interacting with ultrashort intense laser fields are often theoretically studied using the single active electron approximation (SAE). We present here results of simulations within Time Dependent Density Functional Theory which address the multielectron nature of the studied systems. The results exhibit multielectron effects in form of orbital coupling and non-adiabatic electron dynamics in electron localization, high harmonic generation and ionization of N+ 2 interacting with a strong laser pulse.


Tunable Surface Interactions In Adsorbing Polymer Solutions, Sorour Hosseini Jan 2018

Tunable Surface Interactions In Adsorbing Polymer Solutions, Sorour Hosseini

Open Access Theses & Dissertations

A simple formalism is suggested, to calculate the most likely configuration of a finite polymer, between two surfaces on which the monomers can adsorb. Grafted polymers typically enhance the stability of colloidal dispersions, via the long ranged steric repulsion due to the overlap of their polymer brushes, which can be thicker that the typical range of the DLVO interactions. However, if the polymers are adsorbing on the colloidal surfaces, there is the possibility of bridge formation between particles and therefore long-range attractions are induced (a procedure commonly used for the flocculation of colloidal suspensions). The two effects are competing and ...


Chemical Intuition For High Thermoelectric Performance In Monolayer Black Phosphorus, Α-Arsenene And Aw-Antimonene, Bo Peng, Hao Zhang, Hezhu Shao, Ke Xu, Gang Ni, Jing Li, Heyuan Zhu, Costas M. Soukoulis Jan 2018

Chemical Intuition For High Thermoelectric Performance In Monolayer Black Phosphorus, Α-Arsenene And Aw-Antimonene, Bo Peng, Hao Zhang, Hezhu Shao, Ke Xu, Gang Ni, Jing Li, Heyuan Zhu, Costas M. Soukoulis

Ames Laboratory Accepted Manuscripts

Identifying materials with intrinsically high thermoelectric performance remains a challenge even with the aid of a high-throughput search. Here, using a chemically intuitive approach based on the bond-orbital theory, three anisotropic 2D group-V materials (monolayer black phosphorus, alpha-arsenene, and aW-antimonene) are identified as candidates for high thermoelectric energy conversion efficiency. Concepts, such as bond length, bond angle, and bond strength, are used to explain the trends in their electronic properties, such as the band gap and the effective mass. Our first principles calculations confirm that high carrier mobilities and large Seebeck coefficients can be obtained at the same time in ...


Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material For 29si Magnetic Resonance Imaging, Hyeonglim Seo, Ikjang Choi, Nicholas Whiting, Jingzhe Hu, Quy S. Luu, Shivanand Pudakalakatti, Caitlin Mccowan, Yaewon Kim, Niki Zacharias Millward, Seunghyun Lee, Pratip Bhattacharya, Youngbok Lee Dec 2017

Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material For 29si Magnetic Resonance Imaging, Hyeonglim Seo, Ikjang Choi, Nicholas Whiting, Jingzhe Hu, Quy S. Luu, Shivanand Pudakalakatti, Caitlin Mccowan, Yaewon Kim, Niki Zacharias Millward, Seunghyun Lee, Pratip Bhattacharya, Youngbok Lee

Nicholas Whiting

Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for 29Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their 29Si MR signals; the particles demonstrated long 29Si spin-lattice relaxation (T1) times (~25 mins), which suggests potential applicability for medical imaging. Furthermore, 29Si hyperpolarization levels were sufficient to allow 29Si MRI in phantoms. These results underscore the potential of porous ...