Promoting sugar’s magnetic attraction

Sugar gets a bad rap. If it’s not being blamed for rising Type 2 diabetes levels, it’s the main cause of obesity in children.

So it’s refreshing to hear that simple sugars are now helping to make a positive impact on human health through their use in cell surface recognition.

Sugar-coated nano-magnets are a novel new way to kill cancer cells by targeting their sweet tooth. Research at the nano-scale is, once again, leading to exciting advances in bio-medics.

Mutual recognition between different cells normally takes place through an interaction or exchange between corresponding surface molecules or, perhaps, membrane glycoproteins.

SFI-funded research from DCU into a new method of coating magnetic nanoparticles with high densities of any simple sugars may be used for magnetic resonance imaging as well as MRI-based detection and killing of circulating cancer cells.

Nano-magnets
Nano-magnets are already being used in several different areas of nanotechnology research: information storage, power supply, binary logic and laser technology.

"The magnets are made of iron oxide [rust]," explains Dr Dermot Brougham, Head of the Nuclear Magnetic Resonance (NMR) and Materials Group School of Chemical Sciences at DCU who is working in collaboration with Dr Andreas Heise, from the Polymer Research Group, also from DCU.

“Rust is at their core as a hard crystal, covered outside by a polymer of amino acids. We then use click chemistry [a lego like practice of chemical tailoring to generate compatible binding units] to coat the particles with simple sugars.”

Sweet nano-magnets are tiny – 10 nanometres across to be precise. Because they are all magnetic, when you put them in a field they line up in a row, making them extremely valuable for bio-medics.

“Magnetic targeting is a really useful tool” says Brougham. “Their attraction to an external magnet means you can locate them easily within the body.

“Once they’re inside the body, the presence of the sugars on the magnets will make them attractive to certain cells such as some cancer cells.

“You can then heat the magnetic particles by applying alternating magnetic fields, which kill the cells but leave the surrounding tissues intact.”

Identify disease
In addition, sweet nano-magnets can be tracked through MRI scanning. They can make a tumour appear brighter in an image, or darker if they aggregate in clusters.

“If you perform an MRI and the nano-magnets localise on a cancer, you’ll be able to identify the disease earlier,” says Brougham.

There are no side effects to ingesting sweet nanomagnets as iron oxide is biocompatible. “It’s already in the body, and is known to be non-toxic at the concentrations used,” says Brougham.

“There are contrast agents already used in MRI – such as gadolinium agents – which are toxic if broken down by the body to release the toxic gadolinium atom. Iron-oxide is, in fact, better as it will break down to iron but that which is not toxic.”

As a result sweet nano-magnets could be administered multiple times: for instance in re-imaging a patient during recovery.

Work on nano-magnets has been ongoing for some time but it’s beginning to move past the pilot stages. Much of the research is now aimed at copper fastening approaches so that this technology may soon become the norm. “Essentially we are trying to make the nano particles better – more magnetic, more crystalline and control the surface chemistry,” he adds.

Bio recognition
The key development made in DCU has been in finding a way to stop the particles from sticking together. "The real innovation in our research lies in how it allows you to disperse the magnets with bio recognition molecules (the sugars) to target the cancer cells.

Our innovation is the greater potential for bio recognition. Sweet nano-magnets use glycol-peptides to stabilise the process – a long chain of amino acids located on the backbone of the magnet. We could click any type of sugar we like onto them.

But this technology isn’t limited to sugars. You could also click a dye or, more importantly, drug molecules onto the particles which could be sent directly to an affected area. We have an SFI grant allowing us to explore these possibilities.”

This preliminary research into bio recognition was published earlier this year in the chemistry journal Angewandte Chemie International Edition