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Quantum Dots May Be Toxic To Cells And Environment Under Certain Conditions

Date:
January 31, 2009
Source:
American Chemical Society
Summary:
Researchers in Texas are reporting that quantum dots (QDs) -- a product of the revolution in nanotechnology increasingly used in electronics, solar cells, and medical imaging devices -- may be toxic to cells under acidic or alkaline conditions. Their study is the first to report on how different pH levels may affect the safety of QDs.

Researchers in Texas are reporting that quantum dots (QDs) — a product of the revolution in nanotechnology increasingly used in electronics, solar cells, and medical imaging devices — may be toxic to cells under acidic or alkaline conditions. Their study is the first to report on how different pH levels may affect the safety of QDs.

In the new study, Pedro Alvarez, Shaily Mahendra, and colleagues note that QDs are semiconductor nanocrystals composed of a metal core surrounded by a shell composed of zinc or cadmium sulfide. Scientists are increasingly concerned that these submicroscopic dots, about 1/50,000th the width of a human hair, could decompose during normal use or after disposal. That decomposition could release toxic metals into the environment, posing a health risk to humans and animals.

To explore this concern, the scientists exposed two common types of bacteria that serve as models of cell toxicity and indicators of environmental health to QDs under different conditions of acidity and alkalinity. At near neutral pH levels, bacteria exposed to QDs experienced decreased rates of growth, but did not die.

However, at moderately acidic or alkaline conditions, many of the QD-exposed bacteria died as QDs shells decomposed, releasing their content of toxic metals. However, proteins and natural organic matter may be able to mitigate toxicity by complexing metal ions or coating particles.

The study cautions, “the release of toxic inorganic constituents during their weathering under acidic or alkaline conditions in the human body or the environment may cause unintended harm that might be difficult to predict with short-term toxicity tests.”


Story Source:

The above story is based on materials provided by American Chemical Society. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mahendra et al. Quantum Dot Weathering Results in Microbial Toxicity. Environmental Science & Technology, Jan 15, 2009; 42 (24): 9424 DOI: 10.1021/es8023385

Cite This Page:

American Chemical Society. "Quantum Dots May Be Toxic To Cells And Environment Under Certain Conditions." ScienceDaily. ScienceDaily, 31 January 2009. <www.sciencedaily.com/releases/2009/01/090128214342.htm>.
American Chemical Society. (2009, January 31). Quantum Dots May Be Toxic To Cells And Environment Under Certain Conditions. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2009/01/090128214342.htm
American Chemical Society. "Quantum Dots May Be Toxic To Cells And Environment Under Certain Conditions." ScienceDaily. www.sciencedaily.com/releases/2009/01/090128214342.htm (accessed July 24, 2014).

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