Sunday, June 3, 2018
F. Bou-Abdallah, Organizer
E. Andreescu, Organizer, Presiding
Session sponsored by Shimadzu
8:15 . Directional templating of anisotropic nanoparticles using poly (pyromellitic dianhydride-p-phenylene diamine) O.A. Sadik
8:50 . Evaluating the environmental health and safety impact of engineered nanomaterials. W.K. Boyes
9:25 . Methodology development for rapid screening and assessment of environmental chemical processes and impact of engineered nanoparticles. E. Andreescu
10:15 . Nanotechnology in the environment: Understanding and exploiting the wet/dry interface. V.L. Colvin
NENM 49: Directional templating of anisotropic nanoparticles using poly (pyromellitic dianhydride-p-phenylene diamine)
Omowunmi A. Sadik1,2, email@example.com. (1) State Univ of New York Suny, Binghamton, New York, United States (2) Center for Research in Advanced Sensing Technologies & Environmental Sustainability (CREATES), Binghamton, New York, United States
Research into anisotropic nanomaterials has significantly increased due to their potential applications in cancer cell imaging , surface enhanced Raman scattering, sensors, optical contrast agent, photochemical cancer therapy among other applications. Anisotropic nanomaterials are a class of materials whose structures, properties, and functions are direction-dependent. This presentation will focus on the use of poly (pyromellitic dianhydride-p-phenylene diamine) (PPDD) as a reducing & stabilizing agent, immobilization matrix, and directional template for the synthesis of anisotropic silver nanoparticles (AgNPs). It will also discuss a new physical insight into the mechanisms of directional templating of anisotropic nanoparticles based on diffusion limited aggregate model and coalescence growth mechanism. Molecular dynamics (MD) simulations and density functional theory (DFT) calculations were performed to provide insight into possible conformation of PPDD monomer. Anisotropic (non-spherical) peanut-shaped, nanorods and dendritic nanostructures were prepared in situ using varying concentrations of precursors from 0.1% w/v to 1.0 % w/v within PPDD matrix. The PPDD served as the reducing and directional template, thus enforcing preferential orientation. The mechanism of formation and growth of the polymer-mediated anisotropic nanoparticles was confirmed using transmission electron microscopy (TEM), UV-vis near-infrared absorption spectra (UV-vis-NIR), and X-ray diffraction (XRD).
NENM 50: Evaluating the environmental health and safety impact of engineered nanomaterials
William K. Boyes, firstname.lastname@example.org. Toxicity Assessment Division, US Environmental Protection Agency, Research Triangle Park, North Carolina, United States
Engineered nanomaterials (ENM) are a fundamental and growing component of the global economy, and are projected to reach an annual economic impact in the hundreds of billions of dollars. Their spreading use far outpaces our ability to evaluate potential for adverse impacts on environmental health and safety. We developed a framework to evaluate the health and safety implications of ENM releases into the environment. Considerations encompassed potential releases of ENM to the environment across product life cycles, fate, transport and transformations in environmental media, exposed populations, and possible adverse outcomes. The framework was structured as a series of compartmental flow diagrams to guide future development of quantitative predictive models, identify research needs, and support development of tools for making risk-based decisions. If released, most ENM are not expected to remain in their original form due to reactivity and/or propensity for hetero-agglomeration in environmental media. Therefore, emphasis was placed transformations of ENM that might occur in environmental or biological matrices. Predicting the activity of ENM is difficult due to the multiple dynamic interactions between the physical/chemical aspects of ENM and similarly complex environmental conditions. Therefore, the use of simple predictive functional assays was proposed as an intermediate step to address the challenge of predicting environmental fate and behavior of ENM. The nodes of the proposed framework reflect phase transitions that could be targets for development of such assays. Application, refinement, and demonstration of the framework, along with an associated knowledgebase that includes targeted functional assay data, will someday allow better de novo predictions of potential ENM exposures and adverse outcomes. Only by developing an efficient ability to forecast and avoid potential environmental health and safety problems across the life cycle of ENM development, use and disposal, can we fully realize the many potential societal benefits promised by the nanotechnology revolution.
This is an abstract of a proposed presentation and does not reflect EPA policy.
NENM 51: Methodology development for rapid screening and assessment of environmental chemical processes and impact of engineered nanoparticles
Emanuela Andreescu, email@example.com. Clarkson University, Potsdam, New York, United States
Applications of engineered nanoparticles in electronics, catalysis, solid oxide fuel cells, medicine and sensing continue to increase. Traditionally, nanoparticle systems are characterized by spectroscopic and microscopic techniques. These methods are cumbersome and expensive, which limit their routine use for screening purposes. This presentation will describe development of novel rapid and inexpensive methods for evaluating the fundamental surface properties, toxicity, functionalization and reactivity of metal and metal oxide nanoparticles and their impact in environmental systems. We will demonstrate the potential of this approach for the: 1) assessment of surface reactivity of redox active nanoparticles, 2) monitoring surface adsorption/desorption and speciation at single particle surfaces, and 3) as a method enabling rapid screening and toxicological risk evaluation of nanoparticles and their mechanisms. The proposed methodology can be used as a predicting tool for the characterization of nanomaterials and assessment of toxicological risks before implementation in large scale applications. Potential advantages and limitations of this approach as a method for the routine study of nanoparticles and nanoparticle systems will also be discussed.
Vicki L. Colvin, firstname.lastname@example.org. Chemistry, Brown University, Providence, Rhode Island, United States
Nanotechnology is no longer an emerging area of study. It is now a well-established research topic that spans nearly all scientific and engineering disciplines, as well as a broad technology sector with many tangible commercial products. Given its position as both a powerful driver of novel science and technologies, the intersection of nanotechnology and environmental research presents many interesting challenges and opportunities which will be illustrated in this talk. Nanotechnology is based on manipulating and applying materials with dimensions between 1 and 100 nanometers; at this scale, materials exhibit special optical, magnetic and chemical properties which are often size-tunable. Applications of nanotechnology exploit these novel material features and thus provide fresh approaches to classic problems such as the efficient treatment of water and the remediation of contaminants from matrices as diverse as soils and aquifers. While these applications use nanomaterials in contained settings, they make it possible to envision the widespread distribution of nanomaterials into our environment.
The fate and implications of such exposures is a fascinating question. Conventionally specialized materials such as silicon or cerium oxide interact with biological and environmental systems as bulk solids. The small size of nanomaterials means that these materials can now move more readily in the environment or the body, and that they can interact with biological systems. They in effect create a highly active interface between 'dry' typically crystalline solids and the complex 'wet' environment. This can be fully exploited in both medicine and catalysis as will be illustrated by cerium oxide. It can also create challenges if the wet/dry interface leads to material dissolution and the release of metal ions. As an example silver nanoparticles exhibit more rapid and extensive dissolution as their dimensions shrink; because their toxicity is the result of silver ions released in dissolution, this can have consequences for their long-term impacts. Much of this size-dependent dissolution, and as a result anti-microbial activity, can be anticipated based on fundamental models of solid state dissolution. It can also be manipulated through surface engineering which of practical importance to the safe and efficient use of silver nanoparticles as disinfection agents.