Nanodiamonds help antidotes reach the brain in laboratory tests

ERR reported that researchers at Tallinn University of Technology, working with colleagues in the Czech Republic and the United States, have developed a nanodiamond-based drug carrier that crossed a blood-brain barrier model in laboratory tests.

The researchers attached oximes, antidotes used against nerve agents, to nanodiamonds. In vitro tests showed that the compounds could pass through the model barrier and restore the activity of the acetylcholinesterase enzyme in the central nervous system after it had been blocked by nerve agents.

Why drugs struggle to reach the brain

The blood-brain barrier protects the brain and keeps its sensitive environment stable. It allows necessary substances to enter while preventing many other molecules, including medicines, from passing through.

This makes it difficult to treat poisoning by nerve agents such as sarin, Novichok and VX, as well as by certain pesticides. Nerve agents can paralyse the human nervous system within minutes by blocking acetylcholinesterase, an enzyme that helps nerve cells transmit signals.

When the enzyme is blocked, victims quickly develop seizures and respiratory failure, which can lead to death.

Oximes used as antidotes can successfully restore the enzyme’s activity in the peripheral nervous system, but their effect in the central nervous system has so far been limited. Because the drug molecules carry a positive charge, they have difficulty crossing the blood-brain barrier. As a result, the medicine may save a patient’s life without preventing brain damage.

Oximes have been used for more than 50 years, but researchers have not yet found an effective way to deliver them to the brain.

Nanodiamonds as drug carriers

Led by Yevgen Karpichev, a senior researcher and head of the Sustainable Chemistry and Technology research group, the scientists tested nanodiamonds as carriers for the antidote.

Nanodiamonds are produced through controlled explosions and have a diameter of about five nanometres. By comparison, a human hair is approximately 60,000 to 80,000 nanometres wide.

Their usefulness as drug carriers is not limited to their small size. The crystals have a highly stable and chemically resistant structure, meaning they are difficult to break down and do not react randomly with other molecules. Their surfaces can also be chemically modified so that different molecules, including medicines, can be attached to them.

The researchers have filed a US patent application for the technology. The approach is still at an early stage of development, but the same principle could eventually be used to deliver other medicines to the brain that are currently difficult to transport to the central nervous system.