Delivering medicine to the brain
Khuloud T Al-Jamal, Serene Tay and Michael Cicirko
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Scanning electron micrograph of a single brain cell (coloured green and pink). A rectangular cut has been made in the cell to watch how tiny, nanometre-sized (1 nanometre = 0.000001 mm) particles (coloured red and brown) interact with its surface. These tiny particles are called carbon nanotubes and are nano-sized cylinders made of carbon atoms. They are being researched for their ability to act as carriers to deliver drugs or genes to cells – for example, anticancer medicines to a tumour. This is particularly important in the brain because many medicines cannot easily cross the blood–brain barrier, a protective layer of cells that regulates entry of molecules to the brain. The diameter of the cell is approximately 20 micrometres (0.02 mm).
What are carbon nanotubes, and how are they related to graphene?
Carbon nanotubes and graphene are both made of carbon atoms arranged in a honeycomb pattern. Carbon nanotubes are formed from carbon atoms rolled up into a tube or cylinder with a diameter of about one nanometre. By contrast, graphene is a two-dimensional sheet of carbon one atom thick; it has been described as a ‘wonder material’ because it’s one of the thinnest, strongest materials so far discovered and conducts electricity more efficiently than copper. When layers of graphene are stacked on top of one another, this forms graphite.
Nanotubes are being researched for their ability to act as nanocarriers – tiny particles that can be loaded with specific drugs or genes, then used to deliver them to a specific site in the body. For example, chemically modifying nanocarriers to recognise tumour cells could allow anticancer medicines to be delivered directly to the tumour, bypassing nearby healthy, non-cancerous cells. Delivering therapeutic molecules to the brain (e.g. to treat neurological disease) is challenging, because many drugs cannot easily cross the blood–brain barrier to reach specific areas of the brain. New approaches to drug delivery in the brain will be crucial in helping to tackle many neurological disorders.