A team of scientists from the University of Adelaide is working to determine if chitosan — which is shrimp-derived material that is often used to control the release of medications — could be used to send nanoemulsion formulations to space.

Specifically, the scientists explored whether chitosan could potentially control the delivery of medicine to astronauts in space when exposed to zero gravity.

The StarMed experiment inside the NyMEx Experiment Module, where membrane fluidity is tested under altered gravity conditions. Source: University of Adelaide

In conjunction with the German Aerospace Center (DLR), Institute of Aerospace Medicine, the team of University of Adelaie scientists conducted the so-called StarMed experiment wherein six small glass vials were exposed on a space flight and then the stability of the emulsion on its return to Earth was analyzed. The researchers noted that the same number of identical control vials were also on the ground in both Europe and at the University of Adelaide.

The researchers explained that the nanoemulsions feature oil droplets (that are roughly 0.0001 mm in size) that are dispersed into an aqueous solution and that functioned as carriers of melatonin — which reportedly reduces the bone loss common among astronauts — in this particular experiment,

"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," the researchers explained. "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 colonized by humans for long-term habitation."

Because oil droplets tend to deliver the drug too rapidly, the team added a chitosan layer around them that acted like a barrier and regulated the release of the melatonin. As such, the team is investigating whether the chitosan-layered nanoemulsions are stable in space and function appropriately for melatonin delivery.

Early data suggests that the droplet size and distribution of nanoemulsions absent the chitosan coating increased while nanoemulsions featuring the chitosan coating did not change at all. Meanwhile, small, more consistent droplets likely offer better uptake and medical outcomes, the team suggests.

"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," the researchers concluded.