Many studies addressing the toxicity of silver nanomaterials have found that smaller sized silver nanoparticles are usually more toxic to organisms and in cell culture than particles of larger sizes yet it is not entirely clear why. We investigated the size dependent toxicity of silver nanoparticles by measuring the response of embryonic zebrafish (Danio rerio) following exposure to a library of thirteen distinct silver nanoparticle size distributions with mean diameters between 8.9 nm and 112.6 nm. Data analysis using dose-response modeling revealed that silver nanoparticles (AgNP) induced embryo toxicity that is dependent on the total surface area and not on the mass or particle number in solution. Included in this study is a comparison between embryo toxicity induced by silver nitrate (AgNO3) and AgNPs for cardiovascular endpoints, as well as an investigation into the influence of the chorion on AgNP toxicity. This study demonstrates the importance of using alternative dose metrics in nanotoxicology, and highlights the value of using the embryonic zebrafish to explore nanomaterial structure activity relationships.

Nanotechnology is a new scientific field with many exciting potential applications in medicine, energy development, and daily life. However, due to their size, nanoparticles have many properties that are distinct from their bulk counterparts. Like many new technologies, the environmental implications of its use have not been thoroughly investigated. It has been shown that silver nanoparticles (AgNPs) cause structural abnormalities in developing Zebrafish (danio rerio) (Mohrmann, Lawrence University 2008). Using a TUNEL assay, it becomes apparent that there are no significant differences between the developmental apoptosis of embryos treated with AgNPs and those without treatment. Tamayo Uechi, et. al. have shown that knockdowns of certain ribosomal proteins results in the same phenotypic defects displayed in the nanoparticle-treated embryos. It is possible that interactions between silver nanoparticles (~1 nm) (http://purestcolloids.com/mesoworld.htm) and these ribosomes (~25 nm) (Moore, 2004) are the source of the abnormalities. RT-PCR (real time polymerase chain reaction) shows that the expression of at least one ribosomal protein gene (ribosomal protein 3) is attenuated by the presence of silver nanoparticles. A translation assay shows promise in determining if the nanoparticles also affect translation, but more data must be collected. A potentially useful application of nanoparticles is in the use of fluorescent nanoparticles (quantum dots) in biomedical imaging. The common nanoparticle that is used in these capacities is Cadmium Selenide (CdSe). The concern with these nanoparticles is their toxicity to humans. However, gold nanoparticles have been repeatedly shown to be nontoxic. This suggests that fluorescent gold nanoparticles are a potential nontoxic alternative for medical applications. The question that remains, then, is how best to manufacture these fluorescent gold nanoparticles. By adding dendrimer (regular, highly-branched monomers that leads to a tree-like generational structure), HAuCl4, and a reducing agent (either trisodium citrate, sodium borohydride, or sodium ascorbate) to water, fluorescent gold nanoparticles are synthesized. Not only are these nanoparticles fluorescent, but their size and shape can be predetermined as well by adding variable amounts of methanol or polyethylene glycol. Both the size and shape of fluorescent gold nanoparticles are important variables to consider, as each may affect the fluorescence of the nanoparticles. Along with the size and shape, the addition of dendrimer could influence fluorescence. With so many variables that can be modified, gold nanoparticle synthesis seems to be an ideal introduction to the nanoworld for introductory chemistry classes. The preliminary data suggest the synthesis of different gold nanoparticle shapes and the synthesis of fluorescent gold nanoparticles. Testing the physical properties of the fluorescence and shape of the gold nanoparticles is an ongoing endeavor.

Details the source, release, exposure, adsorption, aggregation, bioavailability, transport, transformation, and modeling of engineered nanoparticles found in many common products and applications Covers synthesis, environmental application, detection, and characterization of engineered nanoparticles Details the toxicity and risk assessment of engineered nanoparticles Includes topics on the transport, transformation, and modeling of engineered nanoparticles Presents the latest developments and knowledge of engineered nanoparticles Written by world leading experts from prestigious universities and companies

- The first reference work ever published on nanostructured biomaterials and their applications. - A unique source of in-depth knowledge of recent advances in applications of nanostructured biomaterials. Most up-to-date emerging aspects of nanobiomaterials and their applications in the field of nanotechnology. - Contains 33 state-of-the-art chapters written by over 70 internationally renowned experts from 10 countries. - About 5,000 bibliographic citations and hundreds of illustrations, figures, tables, chemical structures and equations.

The zebrafish is the most important fish model in developmental and genetic analyses. This book contains 19 review articles covering a broad spectrum of topics, from development to genetic tools. The contents range from early development, the role of maternal factors and gastrulation, to tissue differentiation and organogenesis, such as development of the organizer, notochord, floor plate, nervous system, somites, muscle, skeleton and endoderm. The genetic tools cover morpholino knock-down, transgenics, fish cloning, transposons and genome evolution. The book also includes two chapters on genome mapping and embryonic stem cells in medaka, another important model fish. Summarizing the state-of-the-art studies of the zebrafish model and focusing on the molecular aspects of development, this book is a valuable reference for students learning the basic aspects of the zebrafish model, and for researchers seeking resources in zebrafish research.