Shrimp shell material may control space drug delivery

By sending nanoemulsion formulations on a space flight, scientists are investigating whether chitosan – a material derived from shrimp and widely used to control the release of medications – performs well in controlling medicine delivery when exposed to zero gravity. Their preliminary results suggest that drugs needed by astronauts can be delivered effectively in space.

A team from the University of Adelaide working with the German Aerospace Center (DLR), Institute of Aerospace Medicine, conducted the StarMed experiment by exposing six small glass vials on a space flight and then analysing the stability of the emulsion on its return to Earth. The same number of identical control vials were on the ground in both Europe and Adelaide.

Nanoemulsions comprise oil droplets (0.0001 mm in size) that are dispersed into an aqueous solution, with the oil droplets being the carrier of melatonin in this experiment.

Professor Volker Hessel, who is the Processes Program Leader at the ARC Centre of Excellence in Plants for Space and Research Director at the University of Adelaide’s Andy Thomas Centre for Space Resources, led the experiments with PhD student Modupe Adebowale, of the University of Adelaide and University of Nottingham.

“The first aim of the experiment was to find out how the stability of the dispersed (oil in water) phases behaves under the changed gravitational conditions,” said Professor Hessel.

“We also aimed to find out how the controlled release of the encapsulated drug melatonin behaves under the changed gravitational conditions, with one sample of nano-oil droplets coated by a chitosan layer. 

“In the long-term the goal is to develop stable nanoemulsions with advanced controlled-release kinetics for medical use in space and on planets colonised by humans for long-term habitation.”

The University of Adelaide conducted the experiment with the DLR’s Dr Jens Hauslage. As part of its MAPHEUS 15 mission, DLR launched a sounding rocket from northern Sweden that contained 21 scientific experiments from organisations around the world.

“In this collaboration it was shown again that sounding rockets are a cost-effective and reliable test platform for experiments and technologies under micro- and altered-gravity conditions for preparation of low Earth orbit and deep space missions. Especially with regard to human exploration and life on the Moon and Mars, these experiments are an important preparation to ensure the health of humans in space,” said Dr Hauslage.

DLR's research rocket, launched in November 2024, was the 600th to lift off from the Esrange rocket base.

“As oil droplets deliver the drug too fast, we added a chitosan layer around them, which is a natural, renewable material derived from chitin that forms the shell of shrimps and other crustaceans. This layer acts like a barrier and regulates the release of the melatonin drug,” said Professor Hessel.

Astronauts are known to suffer from bone loss, which can be as much as 25 per cent during a longer stay in space. The drug melatonin reduces the bone loss and has many other positive beneficial health effects.

In order to provide melatonin to astronauts at the right time and dose, a formulation is needed, which means the drug must be put into a matrix that controls its release. Liquid formulations are increasingly taken by astronauts: about 40 per cent of the formulations at the International Space Station are liquid.

“Our experiments are testing whether the chitosan-layered nanoemulsions are stable in space and function well for melatonin delivery,” said Professor Hessel.

“Preliminary data suggest that the droplet size and distribution of nanoemulsions without chitosan coating increased while nanoemulsions with chitosan coating did not change at all. And small, more uniform droplets are desired for better uptake and medical outcomes.

“If confirmed, this would mean that microgravity nanoemulsions with chitosan coating are more stable. It would also mean that vibrations hardly affected the quality of our nanoemulsions with and without chitosan coating.”

As well as the StarMed experiment, the University of Adelaide’s MiniWeed experiment, conducted in collaboration La Trobe University, will test how altered gravity affects duckweed – a plant identified as a potential food source for astronauts.

The StarMed and MiniWeed experiments are part of the ARC Centre of Excellence in Plants for Space, which is headquartered at the University of Adelaide.

For more information about the centre, visit www.plants4space.com