Navigation Links
Nanoparticle toxicity doesn't get wacky at the smallest sizes

CHICAGO -- The smallest nano-sized silica particles used in biomedicine and engineering likely won't cause unexpected biological responses due to their size, according to work presented today. The result should allay fears that cells and tissues will react unpredictably when exposed to the finest silica nanomaterials in industrial or commercial applications.

Nanotoxicologist Brian Thrall and colleagues found that, mostly, size doesn't matter, by using total surface area as a measure of dose, rather than particle mass or number of particles, and observing how cultured cells responded biologically.

"If you consider surface area as the dose metric, then you get similar types of responses independent of the size of the particle," said Thrall, a scientist at the Department of Energy's Pacific Northwest National Laboratory in Richland, Wash. "That suggests the chemistry that drives the biological responses doesn't change when you get down to the smallest nanoparticle."

Nanoparticles are materials made up of spherical particles that are on average 100 to 1,000 times smaller than the width of a human hair. They are being used in tires, biomedical research, and cosmetics. Researchers are exploring these tiny spheres because their physical and chemical properties at that size offer advantages that standard materials don't, such as being able to float through blood vessels to deliver drugs.

But whether these materials are safe for human consumption is not yet clear. Previous work suggested in some cases, nanoparticles become more toxic to cells the smaller the particles get.

Thrall presented this toxicology data on amorphous silica nanoparticles today at the 2009 American Association for the Advancement of Science's annual meeting. He also presented data on which cellular proteins the nanoparticles use to get inside cells.

One difficulty in measuring toxicity is that not everyone agrees which kind of dose unit to compare. Some researchers measure the dose by total weight, some by the number of particles. Neither method distinguishes whether a nanomaterial's toxicity is due to the inherent nature of the material or the particle size under scrutiny.

"Different dose metrics give different impressions of which particles are more toxic," he said.

To find out, Thrall and his colleagues at PNNL measured the dose at which the particles caused a biological response. The biological response was either death of the cell, or a change in which genes the cell turned on and off. They found that when calculating doses by particle number or mass, the amount needed to generate a biological response was all over the map.

They found that the best way to pinpoint how toxic the particles are to cells was to calculate the dose based on the total surface area of the nanomaterial. Only when they considered the surface area of the dose could they predict the biological response.

And the biological response, they found, was very similar regardless of the size of the nanoparticles. Inside cells, some genes responded to nanoparticles by ramping up or down. More than 76 percent of these genes behaved the same for all nanoparticle sizes tested. This indicated to the researchers that, for these genes, the nanoparticles didn't pick up weird chemical properties as they shrunk in size.

"The big fear is that you'd see unique biological pathways being affected when you get down to the nanoscale. For the most part, we didn't see that," said Thrall.

However, the team found some genes for which size did matter. A handful of genes, these fell into two categories: smaller particles appeared to affect genes that might be involved in inflammation. The larger particles appeared to affect genes that transport positively charged atoms into cells. This latter result could be due to metals contaminating the preparation of the larger particles, Thrall suggested.

Overall, the results contribute to a better understanding of what goes on at the nanoscale.


Contact: Mary Beckman
DOE/Pacific Northwest National Laboratory

Related biology news :

1. Novel 3-D cell culture model shows selective tumor uptake of nanoparticles
2. New nanoparticle vaccine is more effective but less expensive
3. Nanoparticle exposures happen, says expert
4. MIT: Remote-control nanoparticles deliver drugs directly into tumors
5. Technique controls nanoparticle size, makes large numbers
6. Astronomy technology brings nanoparticle probes into sharper focus
7. Researchers mimic bacteria to produce magnetic nanoparticles
8. Environmental fate of nanoparticles depends on properties of water carrying them
9. Nanoparticles assemble by millions to encase oil drops
10. MIT: Stripes key to nanoparticle drug delivery
11. New ORNL process brings nanoparticles into focus
Post Your Comments:
(Date:11/4/2015)... November 4, 2015 --> ... report published by Transparency Market Research "Home Security Solutions Market ... Forecast 2015 - 2022", the global home security solutions market is ... by 2022. The market is estimated to expand at ... 2015 to 2022. Rising security needs among customers at ...
(Date:10/29/2015)... , Oct. 29, 2015  Rubicon Genomics, ... for U.S. distribution of its DNA library preparation ... and Rubicon,s new ThruPLEX Plasma-seq kit. ThruPLEX Plasma-seq ... the preparation of NGS libraries for liquid biopsies--the ... diagnostic and prognostic applications in cancer and other ...
(Date:10/27/2015)... -- Munich, Germany , October ... automatically maps data from mobile eye tracking videos created ... that they can be quantitatively analyzed with SMI,s analysis ... , October 28-29, 2015. SMI,s Automated Semantic Gaze ... tracking videos created with SMI,s Eye Tracking Glasses ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... Florida (PRWEB) , ... November 24, 2015 , ... ... biggest event of the year and one of the premier annual events for ... and ran from 8–11 November 2015, where ISPE hosted the largest number of ...
(Date:11/24/2015)... RALEIGH, N.C. , Nov. 24, 2015  Clintrax Global, Inc., ... Raleigh, North Carolina , today announced that the company has ... earnings represented a 391% quarter on quarter growth posted for Q3 ... Kingdom and Mexico , with the ... place in December 2015. --> United Kingdom ...
(Date:11/24/2015)... ... 2015 , ... This fall, global software solutions leader SAP and AdVenture Capital ... and pitch their BIG ideas to improve health and wellness in their schools. , ... win the title of SAP's Teen Innovator, an all-expenses paid trip to Super Bowl ...
(Date:11/24/2015)... 24, 2015 SHPG ) announced today that ... Piper Jaffray 27 th Annual Healthcare Conference in ... at 8:30 a.m. EST (1:30 p.m. GMT). --> SHPG ... will participate in the Piper Jaffray 27 th Annual Healthcare ... Tuesday, December 1, 2015, at 8:30 a.m. EST (1:30 p.m. GMT). ...
Breaking Biology Technology: