The impact of processing on the cytotoxicity of graphene oxide

In-house prepared graphene oxide (GO) was processed via base washing, sonication, cleaning and combinations of these processing techniques to evaluate the impact on the flake morphology, composition and cytotoxicity of the material. The flakes of unprocessed GO were relatively planar, but upon base washing, the flakes became textured exhibiting many folds and creases observed by AFM. In addition to the pronounced effect on the topography, base washing increased the C/O ratio and increased the cytotoxicity of GO on all four cell lines studied determined via the WST-8 assay. Sonicating the unprocessed and base washed samples resulted in smaller flakes with a similar topography; the base washed flakes lost the texture previously observed upon sonication. The sonicated samples were more toxic than the unprocessed sample, attributed to the smaller flake size, but were interestingly less toxic than the base washed, unsonicated sample despite the base washed unsonicated sample having a larger flake size. This unexpected finding was confirmed by a second analyst using the same, and a different source of GO and resulted in the conclusion that the morphology of GO greatly impacts the cytotoxicity. Cleaning the GO reduced the amount of nitrogen and sulfur impurities in the sample but had no significan

Assessing size-dependent cytotoxicity of boron nitride nanotubes using a novel cardiomyocyte AFM assay

As boron nitride nanotubes (BNNTs) find increased use in numerous applications, potential adverse health effects of BNNT exposure are a growing concern. Current in vitro cytotoxicity studies on BNNTs are inconsistent and even contradictory, likely due to the lack of reference materials, standardized characterization methods and measurement protocols. New approaches, particularly with the potential to reliably relate in vitro to in vivo studies, are critically needed. This work introduces a novel atomic force microscopy (AFM)-based cardiomyocyte assay that reliably assesses the cytotoxicity of a well-characterized boron nitride nanotube reference material, code named BNNT-1. High energy probe sonication was used to modify and control the length of BNNT-1. The polymer polyethylenimine (PEI) was used concurrently with sonication to produce stable, aqueous dispersions of BNNT-1. These dispersions were used to perform a systematic analysis on both the length and height of BNNT-1 via a correlated characterization approach of dynamic light scattering (DLS) and AFM. Cytotoxicity studies using the novel cardiomyocyte AFM model were in agreement with traditional colorimetric cell metabolic assays, both revealing a correlation between tube length and cytotoxicity with longer tubes having higher cytotoxicity. In addition to the size-dependent cytotoxicity, it was found that BNNT-1 exhibits concentration and cell-line dependent cytotoxic effects

Global Law Schools on U.S. Models: Emerging Models of Consensus-Based Internationalization or Markets-Based Americanization Models of Global Legal Education

This article examines two substantially irreconcilable approaches to internationalization that are emerging in the United States. The first focuses on globalizing the law school curriculum through internationalization. This approach is congruent with emerging trends in legal education internationalization in Europe. The second approaches internationalization as a market driven competition for influence among dominant domestic legal orders, that is, as nationalist globalization. Internationalization is understood as the extension of the influence of national law outside the national territory and is nicely illustrated by recent efforts to globalize the law school curriculum by internationalizing the conventional U.S. law school curriculum. The principle thesis is this: The global legal education community, led by the Europeans, has been constructing a vision of globalization of legal education that has as its basis the idea of harmonization and convergence of different systems and the development of a new institutional model grounded in harmonized global trends in law. The United States appears to be taking two approaches to this development. After an Introduction, Part II examines the internationalization efforts of U.S. law schools following one of five models: (1) integration; (2) segregation; (3) aggregation; (4) immersion; and (5) multi-disciplinary department models. This project seeks a newer framework for the construction of shared legal structures grounded in joint effort that is not dominated by the approaches off any one state. Part III then examines the ways in which American institutions are also working against this general trend by positing a form of nationalist globalization that has as its foundation the idea that national legal education can go global without globalizing the law taught. Nationalist globalization takes three forms: a focus on the training of lawyers for domestic service whose pedagogical methodologies can be exported, the extraterritorial extension of the U.S. law school system, and the management of post graduate degrees in law for foreign law graduates. In place of harmonization and globalization of law, the American nationalist globalization model grounded in extraterritorial competition for socialization in the laws of the domestic legal order of dominant states. The article ends with an analysis of the consequences of these competing forms of global engagement in legal education. While much of the attention on changes to the American law school environment has focused on internationalization within consensus-based and supplementary programs founded on the internationalization ideal, American law schools have also been developing market-based strategies that are, at their core, fundamentally inconsistent with the internationalization framework.En este artículo se examina dos enfoques sustancialmente incompatibles de la interna-cionalización que están surgiendo en los Estados Unidos. La primera se centra en la globalización del currículo escolar a través de la ley de internacionalización. Este enfo-que es congruente con las nuevas tendencias en la internacionalización de la educa-ción legal en Europa. La internacionalización de los enfoques en segundo lugar como la competencia por el mercado por la influencia entre dominante ordenamientos jurídi-cos nacionales, es decir, la globalización nacionalista. La internacionalización es enten-dida como la extensión de la influencia de la legislación nacional fuera del territorio nacional y está muy bien ilustrado por los recientes esfuerzos para globalizar el currícu-lum escolar la ley por la internacionalización del derecho convencional EE.UU. currículo escolar. La tesis de principio es el siguiente: La comunidad global de educación legal, liderado por los europeos, ha sido la construcción de una visión de la globalización de la educación jurídica, que tiene como base la idea de la armonización y convergencia de los diferentes sistemas y el desarrollo de un nuevo modelo institucional basado en la armonización de las tendencias mundiales de la ley. Los Estados Unidos parecen estar tomando dos enfoques para este desarrollo. Por un lado, algunas instituciones están participando en la internacionalización de la educación. Sin embargo, las institu-ciones estadounidenses también están trabajando en contra de esta tendencia general al plantear una forma de globalización que tiene como fundamento la idea de que la enseñanza del derecho nacional puede ser globalizada y el rechazo de la necesidad de crear y enseñar derecho más allá del derecho nacional. En lugar de la armonización y la globalización del derecho, los estadounidenses de un modelo basado en la competen-cia extraterritorial para la socialización de las leyes del ordenamiento jurídico interno de los estados dominantes