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Assessing Use of Gold Nanoparticles
By: Katie Anderson, Cosmetics & Toiletries
Posted: May 31, 2013, from the June 2013 issue of Cosmetics & Toiletries.
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Mironava noted that the larger nanoparticles, in this case 45 nm, are more toxic than the smaller nanoparticles (13 nm). Therefore, the team used lower concentrations of the colloidal gold solution for the bigger nanoparticles and higher concentrations (seven fold) of the colloidal gold solution for the smaller nanoparticles.
After culturing the pre-adipocytes with the colloidal gold solutions, Mironava noticed many changes to the cellular activity. “The level of different proteins was decreasing. We also found that the migration of the cells and the ability of the cells to contract collagen is suppressed,” noted Mironava. Specifically, the deposition of two main proteins of the extra-cellular matrix (ECM), collagen and fibronectin, is altered. “There is a larger suppression of collagen than the fibronectin, which results in the softening of the ECM.” The consequence of this softening is difficult to determine, according to Mironava, who found that, when cultured with dermal fibroblasts, the gold nanoparticles harden the ECM. “It is difficult to explain the consequence of [the opposite effects] because the change in these two proteins are required to differentiate pre-adipocytes to adipocytes.”
It is clear, however, that the decreased cell migration and decreased ability to contract collagen impact skin healing. “If your skin is wounded, collagen fibers in pre-adipocytes must contract or pull the wound closed. Therefore, wound healing is suppressed with toxic levels of the gold nanoparticles.”
Mironava also added that the gold nanoparticles suppress one of the main functions of pre-adipocytes, fat accumulation. “These cells differentiate themselves into adipocytes by accumulating lipids, but there was less lipid accumulation with the gold nanoparticles,” said Mironava. This inhibition of the differentiation of pre-adipocytes into adipocytes could be attributed to the ability of gold nanoparticles to increase the DLK1 protein, which has been found to inhibit adipogenisis. Mironava noted that this study is not complete, so the researchers do not know the whole story of the adipogenesis inhibition but plan to investigate further over the next five years.
Reversible Effect and Future
The important thing to note, according to Mironava, is that the effects of the gold nanoparticles are reversible at certain concentrations. “When we removed the nanoparticles from the cell culture, in a very short time, two weeks, the cells were able to recover from the concentration we gave them,” added Mironava. “It is important that if certain concentrations are not exceeded, the cells will be able to recover with no side effects.” The properties of the cells had returned to the same as the untreated cells.