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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.
Gold nanoparticles have a wealth of pharmaceutical and medical uses. Notably, the ability of these nanoparticles to absorb light and turn this light into heat has put them at the center of ongoing cancer studies exploring their efficacy in destroying malignant cells. They have even been used as contrast agents in electron microscopy, but their ability to deliver other materials has made them candidates for drug and gene delivery and interesting to explore for inclusion in skin care.
Before you rush off to include gold nanoparticles in your new skin cream; however, brush up on the latest research by Tatsiana Mironava, PhD,* from Stony Brook University, who found that size, concentration and duration of application plays an important part in the toxicity of the material, with the wrong choice leading to a disruption of cell movement, cell replication and collagen contraction. In addition, at the wrong concentration, the gold nanoparticles inhibited the ability of pre-adipocytes to differentiate into mature adipocytes (adipogenesis).
Mironava’s decision to investigate gold nanoparticles was based on their potential in multiple industries. “Nanoparticles are promising because they have unique properties, but it is not clear if gold nanoparticles are completely safe,” she noted. “On the microscale, gold is inert, completely safe and approved for internal medicine, but on the nanoscale, the properties of gold are different.” Many scientists use them, assuming they are safe by analogy because their microscale counterparts are inert, but Mironava notes that scientists must be cognizant of the limitations and toxicity of different size gold nanoparticles.
Mironava’s team tested both 13 nm and 45 nm citrate-coated gold nanoparticles in cultures of adipose-derived stromal cells (pre-adipocytes). The sizes used, according to Mironava, were chosen for their obviously different toxicity levels. “Previous studies indicated that the level of toxicity was very different for these two sizes,” added Mironava, who sought to discover what happened to cells when exposed to toxic levels of gold nanoparticles.
The nanoparticles in a colloidal solution at various concentrations up to 15% v/v were cultured with the pre-adipocytes for allotted amounts of time. “We didn’t want to use more than 15% of the culture medium because we didn’t want to introduce too many variables at one time,” added Mironava. The cellular response was then checked at different time intervals, viewing the effect on protein synthesis and other cell properties such as migration and collagen contraction. It was compared to untreated pre-adipocytes as a control.