Dubai: Nanoparticles, or tiny particles, can be found all around us – some existing in nature, others created by humans. They are at the forefront of materials science and have diverse uses. Because of their sub-microscopic size, they have unique characteristics and are applied in a variety of areas.
Of late, there have been concerns about their use in the food industry and whether they seep into the gut, making them toxic.
Although studies into this are still at an early stage, research has shown that some nanoparticles can be absorbed by the body, making it hazardous to health.
Here’s a closer look at nanoparticles.
What are nanoparticles?
Nanoparticles, as the name suggests, are particles that range between 1 to 100 nanometres in size (compare this to a human hair, which is about 80,000 nanometres thick). Undetectable by the human eye, most of them are made up of only a few hundred atoms.
Do they occur naturally or are they made?
In nature, there are several nanoparticles. A spider's silk is strong because of nanoproteins and a gecko's feet are sticky because of nanohairs.
They can, however, be created, and since they are so small, they offer unique features that make them appealing to a wide range of businesses.
Materials in the nanometre range have been produced for several decades. Today, the production capabilities for specially designed nanomaterials have increased tremendously.
How are they made?
Specific synthesis processes are used to produce various nanoparticles, coatings or composites.
Two basic strategies are used to produce nanoparticles – top-down and bottom-up.
Top-down refers to the mechanical crushing of source material using a milling process.
In the bottom-up strategy, structures are built up by chemical processes.
What are nanoparticles used for?
The small size of nanoparticles and the wide surface area to volume ratios mean that they can be used for a wide range of applications. They can be mixed with other materials to form composite materials with improved properties.
Nanosilver is used to coat medical breathing tubes and bandages, and it can transfer cancer treatments straight into tumour cells. Nanoparticles could direct pesticides to specific sections of a plant or regulate the flow of nutrients from fertilizers.
They can also be used for more mundane purposes. Cosmetics and food contain synthetic nanoparticles. Plasters, exercise leggings and yoga mats contain nanosilver, which is believed to have antibacterial characteristics.
Nanoparticulate materials are used in some sunscreens, paints and cosmetics.
Are nanoparticles safe?
Scientists are concerned that synthetic nanoparticles are released into the environment when household goods are washed or recycled. This, in turn, makes its way into the soil and sea. Synthetic nanoparticles of plastic have been found in the ocean and in ice in both poles. Unlike chemical compounds, they cannot be dissolved.
What about food? Should we be concerned?
In the food industry, nanotechnology can be used to improve food quality, shelf life, safety and nutritional benefits. Some nanomaterials are used in packaging and anti-microbial treatments for sanitising food manufacturing plants.
There has been some concern about the use of engineered nanoparticles into food, such as those used as delivery systems for colours, flavours, preservatives and nutrients, according to Nature website. The research found that many nanoparticles are unlikely to have adverse effects on human health, but there is evidence that some of them could have harmful effects and that future studies are needed.
What types of nanoparticles are found in food?
Nanoparticles in food can be divided according to their composition – organic or inorganic.
Inorganic materials like silver, iron oxide, titanium dioxide, silicon dioxide or zinc oxide are some types of nanoparticles used in food. They also vary in their tendency to dissolve under different solution conditions.
They are used in a variety of applications in the food industry – as antimicrobial agents in foods and packaging materials. There is limited information about the potential toxicity of silver nanoparticles ingested with foods. However, several animal studies have reported that silver nanoparticles can accumulate in various organs after ingestion, including the liver, kidneys, spleen, stomach and the small intestine, according to Nature.
Titanium dioxide nanoparticles
These particles are used as functional ingredients in certain foods to provide optical properties like increased lightness and brightness. Chewing one piece of chewing gum can result in an intake of 1.5-5.1mg of titanium dioxide nanoparticles. The amount of these particles consumed was 2-4 times higher for children than adults, probably because many products consumed by children had some of the highest levels of this nanoparticle.
Silicon dioxide nanoparticles
These nanoparticles are added to certain powdered foods to enhance flow properties. Research has suggested that silicon dioxide nanoparticles accumulate in the liver at levels that could cause adverse effects.
These are primarily composed of organic substances, such as lipids, proteins or carbohydrates. In general, they are thought to be less toxic than inorganic ones.
These are widely present in many food products, like soft drinks and fruit juices. Different types of lipid nanoparticles may be present in foods including oil droplets and fat crystals.
Casein micelles, which are tiny clusters of casein molecules and calcium phosphate ions present in bovine milk and other dairy products, are the most prevalent protein nanoparticles discovered in meals. There is minimal concern regarding the possible toxicity of this form of nanoparticle because it has been widely ingested by people for centuries.
The difficulties related to finding organic nanoparticles within complicated biological matrices has meant that few studies have been done. There is need for more research on the destiny and toxicity of organic nanoparticles following absorption.