Interfacial charge transfer between CdTe quantum dots and Gram negative vs. Gram positive bacteria.

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Environ. Sci. Technol.

DOI:https://doi.org/10.1021/es902898d· OSTI ID:971487

Dumas, E; Gao, C; Suffern, D; Bradforth, S E; Dimitrejevic, N M; Nadeau, J L

Oxidative toxicity of semiconductor and metal nanomaterials to cells has been well established. However, it may result from many different mechanisms, some requiring direct cell contact and others resulting from the diffusion of reactive species in solution. Published results are contradictory due to differences in particle preparation, bacterial strain, and experimental conditions. It has been recently found that C{sub 60} nanoparticles can cause direct oxidative damage to bacterial proteins and membranes, including causing a loss of cell membrane potential (depolarization). However, this did not correlate with toxicity. In this study we perform a similar analysis using fluorescent CdTe quantum dots, adapting our tools to make use of the particles fluorescence. We find that two Gram positive strains show direct electron transfer to CdTe, resulting in changes in CdTe fluorescence lifetimes. These two strains also show changes in membrane potential upon nanoparticle binding. Two Gram negative strains do not show these effects - nevertheless, they are over 10-fold more sensitive to CdTe than the Gram positives. We find subtoxic levels of Cd{sup 2+} release from the particles upon irradiation of the particles, but significant production of hydroxyl radicals, suggesting that the latter is a major source of toxicity. These results help establish mechanisms of toxicity and also provide caveats for use of certain reporter dyes with fluorescent nanoparticles which will be of use to anyone performing these assays. The findings also suggest future avenues of inquiry into electron transfer processes between nanomaterials and bacteria.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF; EPA GRANT; National Science and Engineering Research Council of Canada; Canadian Institutes of Health Research Grant
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 971487
• Report Number(s): ANL/CSE/JA-66023
• Journal Information: Environ. Sci. Technol., Journal Name: Environ. Sci. Technol. Journal Issue: 2010 Vol. 44; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS
BACTERIA
CELL MEMBRANES
DEPOLARIZATION
DIFFUSION
DYES
ELECTRON TRANSFER
FLUORESCENCE
HYDROXYL RADICALS
IRRADIATION
MEMBRANES
PRODUCTION
PROTEINS
QUANTUM DOTS
STRAINS
TOXICITY