End-markets power halloysite forward

By John Ollett
Published: Thursday, 05 July 2012

Halloysite finds its niche in cosmetics and cancer cures

Halloysite is traditionally viewed as a simple ceramic mineral but great strides have been made recently in end-uses that take advantage of halloysite’s unique mineral structure that range from nail polish, to cancer cures, and body armour.

Halloysite is a rare clay that is a member of the kaolin family of aluminosilicates and is mined in very few places in the world.

The majority of world production is mined at a well established Imerys mine in New Zealand and a relatively new mine belonging to Applied Minerals in Utah, US.

The Imerys deposit is used chiefly for ceramics and is part of Imerys Tableware New Zealand while the Applied Minerals deposit focuses on a variety of end markets including fire retardants, polymer composites, paints and coatings, and agriculture.

Halloysite – a unique mineral

Halloysite’s benefits lie in its nanotube structure. Halloysite natural tubules are ultra-tiny hollow tubes with diameters typically smaller than one tenth of a micron (100 billionths of a meter), with l

 
 Imerys' halloysite mine in Matauri Bay, New Zealand
engths typically ranging from about half of a micron (millionths of a meter) to over five microns. The hollow opening (lumen) of a nanotubes is approximately 20 nanometers.

This nanotube structure is believed to be the result of hydrothermal alteration, or surface weathering of other aluminosilicate minerals (such as kaolin).

Significantly, halloysite nanotubes do not require large amounts of chemical modification or complex chemical processes, such as intercalation and exfoliation, in order to produce stable nanoparticle clay dispersions.

NaturalNano, a major processor of halloysite, have found that this makes it possible to obtain performance improvements without the complexity and processing cost associated with other nanotubes.

These nanotubes give halloysite its great advantages and are the key to the advances being made in its end-markets.

NaturalNano

US-based NaturalNano Inc. is a major player in the halloysite markets and the primary supplier of halloysite clay to further downstream companies.

The company, which has a plant in Rochester, New York, also processes halloysite clay for its own range of products.

 
 NaturalNano's lab in Rochester, New York
Credit: NaturalNano


It does this by using “Extended Release” technology. This system loads the nanotubes with relevant substances for the end product and then mixes the loaded nanotubes with the end product.

The benefit of using nanotubes lies in the way they diffuse, NaturalNano says. Diffusion from a tube is different to diffusion from a sphere due to the relationship between volume and surface area.

Tube diffusion is much closer to zero order release which means continuous and even release over time, which would not necessarily occur with a standard spherical release mechanism.

NaturalNano sources its halloysite from a producer outside of the US. It “has it processed here [Rochester plant] and then it is ready to be utilised,” CEO James Wemett told IM.

NaturalNano’s technology can remove impurities from halloysite using source material from a number of different deposits.

The final product, after loading of the nanotubes, can be provided as a dry powder or in a liquid solution.

If necessary, the halloysite nanotubes in the final product can be enclosed in a polymer which slows the diffusion.

Nail varnish

NaturalNano has found a niche in cosmetic nail varnish products and recently announced a three year exclusive agreement with Parisian varnish manufacturer Fiabila SA.

 

NaturalNano's halloysite is
used in Sally Hansen
nail products

Credit: nerissa's ring



The company load the halloysite nanotubes with certain propriety products which improve the adhesion and flow of the nail polish, Wemett told IM.

These nanotubes are mixed into the Sally Hansen line of nail polishes (manufactured by Fiabila for Coty), an extremely popular range of nail products.

The unique delivery system that halloysite presents gives NaturalNano an edge, its CEO stressed: “A lot of our customers are using some type of clay today but it is not doing what they need it to do, and that is our niche.”

NaturalNano continues to develop products for new customers and explore new market areas but, significantly, this takes time.

“It takes [companies] a long time to get to the point where halloysite nanotubes become a commercial product,” said Wemett. It took about a year and a half for Fiabila to begin using the nanotubes commercially and other Fortune 500 customers will have similar lead in times.

Wemett remains positive about the company’s opportunities and highlights the continued development of new products for new customers at the company’s research lab in its Rochester, headquarters.

Targeting of cancer cells

Halloysite hasn’t just found itself an important niche in the cosmetics industry but has also helped medical research make strides forward in using halloysite to target circulating tumour cells within the body.

Cancer metastasis is when a tumour spreads to different parts of the body via circulating tumour cells which are released into the bloodstream and flow to another part of the body where they stick to a surface (such as organs).

It is a serious development in cancer and can prove fatal but halloysite could provide the key to detection and eventual manipulation of cancer cells.

“We have been developing some procedures to try and isolate and detect tumour cells in the blood stream,” Michael R. King, associate professor of biomedical engineering at Cornell University, US, told IM.

King’s department at Cornell have been pioneering this process and a recent research article in medical journal Clinical Chemistry brought the process to light.

  In the interest of the advancement of science, professor King has distributed a short seven minute video showing the public and any other researchers how to use this halloysite targeting with objects that be bought over the counter. To watch the video – click here


Detecting circulating cancer cells is very difficult King explained: “The cancer cells are very very rare. In a millilitre of blood you might have one or two cancer cells mixed in with a million white blood cells and a billion red blood cells.”

To do this King creates surfaces that mimic the interior surface of blood cells which cancer cells adhere to in the body. The adhesion does not come from halloysite but instead from a group of proteins called selectins.

Halloysite’s benefit lies in that a layer of it applied to the created surface basically repels the numerous white blood cells that accumulate as the body’s immune system activates.

In doing this, it greatly increases the purity of tumour cells in the sample and as such means that circulating tumour cells can be targeted with ease.

Practical applications

This purity opens up a whole range of options for research and practical applications.

As halloysite does not allow the accumulation of white blood cells it could be used as biomaterial: “Especially things that are designed to be implanted, from catheters to stents. Anything that is in contact with blood and is designed to be there for a long time.”

The halloysite will help to prevent the immune system from attacking the foreign body and so, could have a wide range of applications in the medical industry, including in preventing the body attacking implants.

The halloysite nanotubes could also be packed with cancer drugs, much like the NaturalNano cosmetic applications, that would treat the cancer and have a slow controlled release.

 
 Halloysite, the wonder material
But the most significant of these applications is the manipulation of circulating cancer cells.

Once the cells are detected and isolated they could be targeted, King outlined. This application requires much more research but promising results have already occurred.

A protein called trail (TNF-related apoptosis-inducing ligand) can be adhered onto the surface that the cancer cells stick to and programme the cancer cells to die (apoptosis is the name of this process).

While this is not strictly a cancer cure, it would prevent the cancer from metastasising around the body and forming new cancers.

King pointed out that the pipeline for this is significant – around the decade mark – but that the current mice experiments were showing good results that may be published shortly. In several years, human trials could begin, he said.



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