Thursday, May 31, 2012

A pilot study in non-human primates shows no adverse response to intravenous injection of quantum dots

Nature Nanotechnology

Quantum dots have been used in biomedical research for imaging, diagnostics and sensing purposes. However, concerns over the cytotoxicity of their heavy metal constituents and conflicting results from in vitro and small animal toxicity studies have limited their translation towards clinical applications.

Here, in this paper, a pilot study that rhesus macaques injected with phospholipid micelleencapsulated CdSe/CdS/ZnS quantum dots do not exhibit evidence of toxicity. Blood and biochemical markers remained within normal ranges following treatment, and histology of major organs after 90 days showed no abnormalities. These results showed that acute toxicity of these quantum dots in vivo can be minimal. However, chemical analysis revealed that most of the initial dose of cadmium remained in the liver, spleen and kidneys after 90 days. This means that the breakdown and clearance of quantum dots is quite slow, suggesting that longer-term studies will be required to determine the ultimate fate of these heavy metals and the impact of their persistence in primates.

Molecular Level Ordering in Poly(2-vinylpyridine)

Adv. Mater.
The reaction between atactic poly(2-vinylpyridine) and 1,4-dibromobutane leads to formation of long-range 3D molecular ordering in polymer chains mainly because the side group (pyridine) of the polymer chain changes to a syndotactic configuration.
The high voltage electron microscope image is also shown, the dark and gray areas are attributed to regions of high and low electron density, respectively.  They also made micells using P2VP-b-poly(n-hexyl isocyanate) in methanol/THF solution and add 1,4-dibromobutane to crosslink the shell.