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Rice UniversityCBEN
Center for Biological and Environmental Nanotechnology
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Biological Interactions with Engineered Nanoparticles in the Environment

No uptake of QDs in Gram Positive Bacteria

No uptake of Quantum Dots into Gram Positive Bacteria.

The widespread applications of engineered nanomaterials in diverse industries and commercial products require timely research into their potential health and environmental impacts to ensure ecologically-responsible manufacture, use, and disposal. Here, we evaluated (1) the bioavailability and bioaccumulation of C60 in the earthworm Eisenia foetida; (2) the adverse biological impacts of nanoscale zero-valent iron (NZVI) on Dehalococcoides spp during chemical-biological treatment of groundwater contaminated by chlorinated ethenes; (3) the genetic response of bacteria to the presence of quantum dots (QDs) at toxic but sublethal concentrations and (4) the uptake, biodistribution, and accumulation of QDs in Daphnia magna. Using 14C-labeled C60 whose radioactivity enables C60 fullerene to be traced in biosystems, we showed that C60 was readily accumulated in earthworm tissue. We demonstrated that polymer coating on NZVI could prevent the inhibitory effect of NZVI on Dehalococcoides spp (a genus associated with reductive dechlorination of chlorinated ethenes), despite loss of the coating after the long-term exposure and thereby toxicity recurrence. As a follow-up study on antibacterial and antifungal activities of QDs, we explored the genetic basis of toxicity by monitoring gene expression in P. aeruginosa exposed to intact and weathered QDs. We also exploited the unique fluorescence properties of QDs to demonstrate the use of fluorescence confocal laser scanning to track in vivo and in real time QD uptake and accumulation in Daphnia magna.

Participating Researchers: