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Rice UniversityCBEN
Center for Biological and Environmental Nanotechnology
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The Biology of Engineered Nanoparticles—From Proteins to Organisms

In vivo Particle Tracking

In vivo Particle Tracking: Quantum Dots within Daphnia magna.

Last year CBEN consolidated those projects concerned with the interactions between nanomaterials and biological systems; these efforts are now housed entirely within Theme 1. Historically, this center has always been concerned with the myriad ways that nanoparticles may unintentionally interact with organisms over multiple length scales.  Within CBEN we often refer to this as looking ‘from the nanometer to the kilometer’ and work to study example systems that include biological membranes, proteins, cells and both mammalian and ecologically relevant organisms.  Work in this area of theme 1 is highly interactive with both theme 2 and theme 3, and we often struggle with where to report out various accomplishments.  This year for example, the work of Drezek and Colvin on studying how quantum dots transport with an ecologically relevant organism could be classified as theme 1, theme 2 or even theme 3.  Aspects are described here and in theme 2. Similarly, our effort to link nanoparticle structure (e.g. size, shape, surface) to in-vitro cellular response has required that we confront explicitly issues of nanocrystal purity in aqueous dispersions.  These analytical methods are reported out in Theme 3 this year, though they will impact immediately cytotoxicity studies ongoing in CBEN.

Accomplishments for this project in the current year include the productive conclusion of a multiyear year collaboration and sponsored research agreement with the non-profit Consumers Union.  Colvin worked with this organization to evaluate possible human exposures to engineered nanoparticles that arise from sunscreens.  Her group has identified in commercial products both ZnO and TiO2 nanocrystals, and details the typical size and phase composition of these materials.  An important finding is that all commercial products that list inorganic pigments as active ingredients contain nanoscale particles – a fact that is not generally available to consumer’s because labels do not need to specify the size range of a material.  Using these same sunscreen-derived pigments, as well as model pigments, the ROS generation capability of the systems have been assessed.  Over the next year, we will transition to in-vitro and in-vivo studies for these materials.  Colvin and Matthews have continued their effort to detail the biochemical identity of model nanoparticle surfaces; this year through protein modification chemistry they were able to establish the chemical origins of non-specific protein interactions with negatively charged metal particles.  Diehl has begun to study using single molecule techniques the intracellular trafficking of nanoparticles; an important feature of this work is the strong focus on engineering the particle interface with membrane transport proteins.  Using phage display techniques, these surfaces will provide not just single proteins but the protein complexes thought to be crucial for specific sub-cellular targeting of materials.

Finally, this project now benefits from the engagement of two young faculty (McNew and Lane) in nanomaterials and CBEN; these young biologists are experts in membrane and developmental biology and provide Theme 1 with a strong disciplinary foundation in fundamental biology.  Already their laboratories are producing preliminary data on the interactions between zebrafish and insect cells with well controlled and characterized nanocrystals; these biological models provide the Lane and McNew groups with the ability to probe in detail sophisticated hypotheses concerning the mechanisms by which nanoparticles interact with both cells and developmental processes. 

Participating Researchers: