5 Oct 2017

Designing nanoparticles to move medication around your body

From Our Changing World, 9:06 pm on 5 October 2017

You’re feeling sick, and your doctor has prescribed some medication. But when you swallow that pill, spare a thought for the drug it contains – and the difficult route it faces to reach its target.

It has to survive the churning acidic maelstrom of your stomach, navigate its way out of your intestine and into the blood stream, before finally reaching its destination, hopefully intact.

Dr Arlene McDowell from the School of Pharmacy at the University of Otago, however, is hoping to come up with a nano-sized delivery system that will be much more efficient.

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Nanoparticles on a single cell.

Clumps of nanoparticles containing a drug (green) clustered on a single cell. Photo: Jasper Chiu / University of Otago

Arlene’s plan is to package up minute amounts of a drug into nano containers. This delivery system will protect the drug from the rigours of the digestive system and ensure that more of the medication gets absorbed out of the gut into the blood. It will also provide a secure address system that takes the drug directly to where it’s needed.

“I think [these nanoparticles] are like a Malteser … we have a polymer wall all around the outside of these particles, and your drug is entrapped within. And those polymers are robust enough to withstand the changes in pH within the stomach and remain intact.”

Designing nano containers

Arlene describes her work as being at the nano-bio interface – “what happens when a nanoparticle comes and touches a cell, and how can you get that nanoparticle taken up more effectively.”

Arlene and PhD student Sarah Streck are studying how different cell-penetrating peptides can be used to deliver the cargo into a cell.

“We decorate the surface of a cell with these peptides, which are meant to enhance the way the way the drug is taken up, and so we get more drug into the body, basically.”

Sarah says she is comparing peptides with different architecture, or structures - a short version, a long version and a multi-branched peptide – to see which is most effective.

A potential use of a nanoparticle delivery system could be for the oral delivery of a drug such as insulin; currently diabetics have to inject insulin under the skin. It could also be used to treat cancers, with specific molecules on the outside of the nanoparticles recognising and targeting cancer cells.

Arlene McDowell

Arlene McDowell Photo: University of Otago

How small is nano?

A nanometre is a millionth of a millimetre.

Arlene says that the nanomolecules she is studying are about 200 nanometres long, and an average cell is 1000-2000 nanometres long.

So even though each nanoparticle will only carry a tiny amount of drug, a single cell will be able to uptake many drug-containing nanomolecules to receive the correct dose.