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Gold nanorods have potential applications as chemical sensing, biological imaging, and photothermal therapeutics. Our laboratory has developed the syntheses of these materials, in controlled size and shape, over the last few years. Surface modification of these nanomaterials is a key step to enable applications. In this talk I will describe our recent efforts to wrap up nanorods with layer-by-layer polyelectrolyte deposition in aqueous solution, in a way that allows for “capture coating” of small molecules at defined distances from the surface; how we can “fix” the surface of the nanomaterials by on-particle polymerization reactions; and how surface ligand exchange and overcoating affects biological properties of these materials.

Understanding of nanoparticle impacts on critical bacteria functions allows us to gain a mechanistic understanding of toxicity and guides us towards design rules for creating safe nanomaterials. Herein and using analytical techniques, biofilm formation, a general bacteria function, and riboflavin secretion, a species-specific function, were monitored in Shewanella oneidensis, a metal reducing bacterium, following exposure to a variety of TiO2 nanoparticle types (synthesized, Aeroxide P25, and T-Eco).  TEM images show that dosed nanoparticles are in close proximity to the bacteria but they are not internalized. Using quartz crystal microbalance (QCM), it was revealed that S. oneidensis biofilm formation is slowed in the presence of nanoparticles.   Though S. oneidensis grows more slowly in the presence of TiO2 nanoparticles, riboflavin secretion, a function related to the S. oneidensis metal reducing capacity, was increased significantly… Read More »Poster: Impact of TiO Nanoparticles on Growth, Biofilm Formation, and Flavin Secretion in Shewanella Oneidensis

Engineered nanoparticles are found in many everyday products and hold great potential as therapeutic agents. Accordingly, it is critical to consider how engineered nanoparticles interact with physiological and ecological systems. This work focuses on functional assessment of bacterial cell behavior following exposure to Au, nanodiamond, and semiconductor nanoparticles. Functional considerations include biofilm formation, cell delivery of chemical messengers, production of reactive oxygen species, and gene expression, among others. In this new collaborative study, obtained bacterial toxicity results can be compared to those o btained in other model systems (lipid bilayers and the multicellular water flea, Daphnia) to identify common modes of nanoparticle interactions and the resultant effects. The goal of this work is to discover critical nanoparticle features that determine… Read More »Invited Talk: Nanoparticle Toxicity Assessment in a Bacterial Model