Tag Archives: silicon dioxide nanoparticles

Metal oxide nanoparticles and negative effects on gut health?

A May 4, 2023 Binghamton University news release by Jillian McCarthy (also on EurekAlert but published on May 9, 2023) announces the research, Note: A link has been removed,

Common food additives known as metal oxide nanoparticles may have negative effects on your gut health, according to new research from Binghamton University, State University of New York and Cornell University. 

Gretchen Mahler, professor of biomedical engineering and interim vice provost and dean of the Graduate School, worked in collaboration with Cornell researchers to study five of these nanoparticles. Their findings were recently published in the Journal of Antioxidants.

“They’re all actual food additives,” said Mahler. “Titanium dioxide tends to show up as a whitening and brightening agent. Silicon dioxide tends to be added to foods to prevent it from clumping. Iron oxide tends to be added to meats, for example, to keep that red color. And zinc oxide can be used as a preservative because it’s antimicrobial.” [emphases mine]

In order to test these nanoparticles, Mahler and Elad Tako, senior author and associate professor of food science in the College of Agriculture and Life Sciences at Cornell, used the intestinal tract of chickens. A chicken’s intestinal tract is comparable to a human’s; the microbiota that they have and the bacterial components have a lot of overlap with the microbiota that you see in the human digestive system, said Mahler. 

“We’ve been testing a series of nanomaterials here at Binghamton, and we’ve been looking at things like nutrient absorption, enzyme expression and some of the more subtle, functional markers,” said Mahler.

The doses of nanoparticles that were tested reflect what is typically consumed by humans. The nanoparticles were injected into the amniotic sac of broiler chicken eggs, which are specifically bred and raised for their meat. These chickens get larger faster, so the effects of the nanoparticles are more obvious earlier in development. The amniotic sac at a certain stage of development flows through the chicken intestine.

“When they hatched, we harvested tissue from the small intestine, the microbiota and the liver,” said Mahler. “We looked at gene expression, microbiota composition and the structure of the small intestine.”

The researchers found more negative effects with silicone dioxide and titanium dioxide. They also found that the nanoparticles had affected the functioning of the chicken’s intestinal lining (called the brush border membrane), the balance of bacteria in their intestinal tract and the chickens’ ability to absorb minerals.

The other nanoparticles had more neutral, or even positive, effects. Zinc oxide appeared to support intestinal development or compensatory mechanisms due to intestinal damage. Iron oxide could potentially be used for iron fortification, but with potential alterations in intestinal functionality and health.

Mahler doesn’t want to suggest that these nanoparticles need to be removed from our diets completely. Their research is meant to provide some information, and allow people to have a better understanding of what’s really in the food they consume.

“We’re eating these things, so it’s important to consider what some of the more subtle effects could be,” said Mahler. “We develop these gut models around this problem to try to understand it, and this collaboration, where we have these complementary methods to try to look at the problem, has been successful.”

Here’s a link to and a citation for the paper,

Food-Grade Metal Oxide Nanoparticles Exposure Alters Intestinal Microbial Populations, Brush Border Membrane Functionality and Morphology, In Vivo (Gallus gallus) by Jacquelyn Cheng, Nikolai Kolba, Alba García-Rodríguez, Cláudia N. H. Marques, Gretchen J. Mahler and Elad Tako. Antioxidants 2023, 12(2), 431, DOI: https://doi.org/10.3390/antiox12020431 Published online : 9 February 2023 (This article belongs to the Special Issue Dietary Supplements and Oxidative Stress)

This paper is open access.

Nanotechnology in the house; a guide to what you already have

A July 4, 2016 essay by Cameron Shearer of Flinders University (Australia) on The Conversation website describes how nanotechnology can be found in our homes (Note: Links have been removed),

All kitchens have a sink, most of which are fitted with a water filter. This filter removes microbes and compounds that can give water a bad taste.

Common filter materials are activated carbon and silver nanoparticles.

Activated carbon is a special kind of carbon that’s made to have a very high surface area. This is achieved by milling it down to a very small size. Its high surface area gives more room for unwanted compounds to stick to it, removing them from water.

The antimicrobial properties of silver makes it one of the most common nanomaterials today. Silver nanoparticles kill algae and bacteria by releasing silver ions (single silver atoms) that enter into the cell wall of the organisms and become toxic.

It is so effective and fashionable that silver nanoparticles are now used to coat cutlery, surfaces, fridges, door handles, pet bowls and almost anywhere else microorganisms are unwanted.

Other nanoparticles are used to prepare heat-resistant and self-cleaning surfaces, such as floors and benchtops. By applying a thin coating containing silicon dioxide or titanium dioxide nanoparticles, a surface can become water repelling, which prevents stains (similar to how scotch guard protects fabrics).

Nanoparticle films can be so thin that they can’t be seen. The materials also have very poor heat conductivity, which means they are heat resistant.

The kitchen sink (or dishwasher) is used for washing dishes with the aid of detergents. Detergents form nanoparticles called micelles.

A micelle is formed when detergent molecules self-assemble into a sphere. The centre of this sphere is chemically similar to grease, oils and fats, which are what you want to wash off. The detergent traps oils and fats within the cavity of the sphere to separate them from water and aid dish washing.

Your medicine cabinet may include nanotechnology similar to micelles, with many pharmaceuticals using liposomes.

A liposome is an extended micelle where there is an extra interior cavity within the sphere. Making liposomes from tailored molecules allows them to carry therapeutics inside; the outside of the nanoparticle can be made to target a specific area of the body.

Shearer’s essay goes on to cover the laundry, bathroom, closets, and garage. (h/t July 5, 2016 news item on phys.org)

Silicon dioxide nanoparticles may affect the heart

This is an interesting piece of research although it’s difficult to draw conclusions since the testing was ‘in vitro’, which literally means ‘in glass’ and in practice means testing cells in a test tube, a petri dish or, possibly, on a slide. That said, this work centering on silicon dioxide nanoparticles, which are increasingly used in biomedical applications, suggests further investigation is warranted. From a Jan. 9, 2015 news item on Azonano,

Nanoparticles, extremely tiny particles measured in billionths of a meter, are increasingly everywhere, and especially in biomedical products. Their toxicity has been researched in general terms, but now a team of Israeli scientists has for the first time found that exposure nanoparticles (NPs) of silicon dioxide (SiO2) can play a major role in the development of cardiovascular diseases when the NP cross tissue and cellular barriers and also find their way into the circulatory system.

A Jan. 8, 2015American Technion Society news release by Kevin Hattori, which originated the news item, describes the research in more detail,

“Environmental exposure to nanoparticles is becoming unavoidable due to the rapid expansion of nanotechnology,” says the study’s lead author, Prof. Michael Aviram, of the Technion Faculty of Medicine, “This exposure may be especially chronic for those employed in research laboratories and in high tech industry where workers handle, manufacture, use and dispose of nanoparticles. Products that use silica-based nanoparticles for biomedical uses, such as various chips, drug or gene delivery and tracking, imaging, ultrasound therapy, and diagnostics, may also pose an increased cardiovascular risk for consumers as well.” [emphasis mine]

In this study, researchers exposed cultured laboratory mouse cells resembling the arterial wall cells to NPs of silicon dioxide and investigated the effects. SiO2 NPs are toxic to and have significant adverse effects on macrophages. a type of white blood cell that take up lipids, leading to atherosclerotic lesion development and its consequent cardiovascular events, such as heart attack or stroke. Macrophages accumulation in the arterial wall under atherogenic conditions such as high cholesterol, triglycerides, oxidative stress – are converted into lipids, or laden “foam cells” which, in turn, accelerate atherosclerosis development.

“Macrophage foam cells accumulation in the arterial wall are a key cell type in the development of atherosclerosis, which is an inflammatory disease” says co-author Dr. Lauren Petrick. “The aims of our study were to gain additional insight into the cardiovascular risk associated with silicon dioxide nanoparticle exposure and discover the mechanisms behind Si02’s induced atherogenic effects on macrophages. We also wanted to use nanoparticles as a model for ultrafine particle (UFP) exposure as cardiovascular disease risk factors.”

Both NPs and UFPs can be inhaled and induce negative biological effects. [emphasis mine] However, until this study, their effect on the development of atherosclerosis has been largely unknown. Here, researchers have discovered for the first time that the toxicity of silicon dioxide nanoparticles has a “significant and substantial effect on the accumulation of triglycerides in the macrophages,” at all exposure concentrations analyzed, and that they also “increase oxidative stress and toxicity.”

A recent update from the American Heart Association also suggested that “fine particles” in air pollution leads to elevated risk for cardiovascular diseases. However, more research was needed to examine the role of “ultrafine particles” (which are much smaller than “fine particles”) on atherosclerosis development and cardiovascular risk.

“The number of nano-based consumer products has risen a thousand fold in recent years, with an estimated world market of $3 trillion by the year 2020,” conclude the researchers. “This reality leads to increased human exposure and interaction of silica-based nanoparticles with biological systems. Because our research demonstrates a clear cardiovascular health risk associated with this trend, steps need to be taken to help ensure that potential health and environmental hazards are being addressed at the same time as the nanotechnology is being developed.

Unfortunately, there seems to be a little exaggeration at work in this news release. For example, I’m not sure how a consumer would go about inhaling a computer chip or more specifically the silicon dioxide nanoparticles embedded in the chip although I can see how someone involved in the manufacture of the chip might be exposed and inhale silicon dioxide nanoparticles. I’m not trying to negate the research but do want to point out that it has limitations.

Here’s a link to and a citation for the paper,

Silicon dioxide nanoparticles increase macrophage atherogenicity: Stimulation of cellular cytotoxicity, oxidative stress, and triglycerides accumulation by Lauren Petrick, Mira Rosenblat, Nicole Paland, and Michael Aviram. Article first published online: 28 NOV 2014 DOI: 10.1002/tox.22084

Copyright © 2014 Wiley Periodicals, Inc.

This article is behind a paywall.