George K. Larsen

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl4) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe2O3-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe2O3. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe2O3-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe2O3 material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe2O3-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe2O3 can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.

Synthetic Strategies for Anisotropic and Shape-Selective Nanomaterials

This chapter gives an overview of the various approaches that have been taken to create anisotropic nanomaterials. The synthetic mechanisms of nanomaterials are being actively pursued due to the unique size and shape dependent properties that can be exploited for a myriad of applications. Nanomaterials have been synthesized in a gamut of shapes, sizes, and compositions. As their synthetic protocol progresses, scientists are becoming more and more creative in the fabrication of nanomaterials with very interesting architectures to tailor their properties for faster electronics, better resolution imaging, more efficient catalysts, among others.

Characterization of Anisotropic and Shape-Selective Nanomaterials: Methods and Challenges

Research into shape-selective and anisotropic nanoparticles is generally motivated by the desire to create better materials for a specific application, and therefore, it is critical to understand how and why shape affects nanoscale properties. Such information can be revealed through analytical experimentation, and this chapter describes characterization methods and challenges associated with analyzing anisotropic and shape-selective nanoparticles. Researchers can typically employ commonly available techniques used in materials characterization. However, in the case of anisotropic and shape-selective nanoparticles, greater concern for orientational and/or shape effects and artifacts should be shown during analyses.

Anisotropic and Shape-Selective Nanomaterials

Globalization of scientific knowledge and technological advances are sparking innovation and creativity across many fields at an unprecedented rate. Ground-breaking discoveries made in the mid-1980s, namely the development of scanning tunneling microscopy and the discovery of buckminsterfullerene, influenced scientists to envision the world at the atomic level and new paradigms emerged: nanoscience and nanotechnology. Through the manipulation of matter at the atomic level, today scientists can create novel materials with unique properties and functionalities. These new materials enable innovative technologies and applications across many fields from engineering to medicine. Globalization of scientific knowledge and technological advances is sparking innovation and creativity across all fields at an unprecedented rate. Nearly every aspect of science and industry is driven to make advances in the (bio)medical fields, computing and electronics, environmental controls and remediation, transportation, energy production, chemical manufacturing, agriculture, and consumer products. The technological revolution [1] that started decades ago with the introduction of electronic devices and silicon-based integrated circuitry [2] changed humanity forever. The information technology insurgency that emerged with the introduction of internet/broadband, personal computers, mobile phones, and email [3] created a global multi-dimensional world. These technologies re-defined the way we live, communicate, travel and experience the world. This burst of technological developments offered unprecedented opportunities for rapid social and economic progress in our society [4]. S.E. Hunyadi Murph (&) National Security Directorate, Savannah River National Laboratory, Aiken, SC, USA e-mail: Simona.Murph@srnl.doe.gov S.E. Hunyadi Murph Department of Physics and Astronomy, University of Georgia, Athens, GA, USA

Nanoscale Materials: Fundamentals and Emergent Properties

As material size decreases into the nano size regime, novel properties arise that are different from their molecular and bulk counterparts. Due to the size and shape effects in this regime, a nanoparticle’s morphology has a profound effect on its properties. This chapter addresses the effect of dimensionality on the optical, electronic, chemical , and physical assets of various nanomaterials and how physical and chemical relationships can be exploited to improve their properties. Delving into the nuances of the different sizes, shapes, and compositions gives one an appreciation of the potential that nanomaterials have to improve upon today’s technologies. As scientists learn to fabricate increasingly more complex nanomaterials, new opportunities develop every day. A detailed discussion on the effect of morphology and nanometric dimensions on materials physico-chemical properties, which lead to novel applications, will be covered in Chapter 5.

Tritium Contamination Prevention Using Sacrificial Materials

Abstract Tritium is produced by irradiating Tritium Producing Burnable Absorber Rods (TPBARs) in a Commercial Light Water Reactor at the Tennessee Valley Authority Watts Bar Reactor 1. The TPBARs are manufactured with strict materials specification for contaminants for all of the components. Despite meeting these requirements, gamma emitting contamination in the form of 65Zn was detected in a glovebox that was designed to contain tritium. A forensic examination of the piping revealed that the zinc was borne from natural zinc. This zinc deposits at an anomalous distance from the extraction furnace based on vapor pressure. A method to capture the zinc was developed that is intended to prevent the further spread of the 65Zn. This method relies on operating filter media at a specific temperature and location. While this approach is acceptable for the facility while it is in limited operation, as the facility undergoes increased utilization, there is a possibility of scheduling conflicts for maintenance and increasing dose to workers. In order to preclude these issues, methods to contain the zinc within the furnace module, an area designed for high radiation dose, were examined and experimental approaches were developed. These approaches used bulk materials and nano-materials deposited on various substrates that are compatible with tritium and the extraction process. These materials were tested to ascertain their zinc capturing capability, capacity, and characteristics. The first generation material was optimized and a process lid has been fabricated for testing.

Porous Iron Oxide Nanorods and Their Photothermal Applications

Iron oxide is a unique semiconductor material, either as a single nanoparticle, or as a component of multifunctional nanoparticles. Its desirable properties, abundance, non-toxicity, and excellent magnetic properties make it a valuable for many applications. Porous iron oxide nanorods are able to transduce light into heat through the photothermal effect. Photothermal heating arises from the energy dissipated during light absorption leading to rapid temperature rise in close proximity to the surface of the nanoparticle. The heating effect can be efficiently harnessed to drive/promote different physical phenomena. In this report, we describe the synthesis and properties of porous Fe3O4 for photothermal applications. We then demonstrate their use as photothermally enhanced and recyclable materials for environmental remediation through sorption processes.

Synthesis and Characterization of Novel Nanothermometers

A straightforward approach was developed for the synthesis of Pd, Pd-Fe2O3, Au-Fe2O3, and Au-Pd-Fe2O3 nanothermometers, using a single SL DNA. These NP-DNA conjugates were characterized using techniques including EDX measurements, ζ-potential of NPs before and after DNA functionalization, electron microscopy studies and fluorescence spectroscopy. The fluorescence studies of the NP-DNA demonstrate the interaction between the NP and the fluorophore, which is quenched in the case of Au-Pd-Fe2O3 NPs and is perhaps enhanced (when compared to AuNPs) in the case of Pd and Pd-Fe2O3 NPs. In order to achieve more accurate and reproducible measurements, designing a system that is able to hold the NP-DNA conjugates at a temperature for a longer period of time to allow them to 12 equilibrate is currently underway. Our studies show that Au-Pd-Fe2O3 NPs are the best candidate material to serve as nanothermometers when compared to Pd, Pd-Fe2O3, and Au-Fe2O3 materials.