Transmission electron micrograph of nano-needles (yellow/green tubular structures) crossing the blood-brain barrier (orange cell layer) carrying therapeutic cargo from the blood (left, purple) to the brain (right, black). The blood brain barrier is a protective layer of cells that regulates entry of molecules to the brain. Despite acting as a protective mechanism, it is a barrier to delivering therapeutic agents to the brain. The nano-needles depicted here are formed from carbon nanotubes (CNTs). CNTs are tubular nanostructures made up of rolled-up layers of graphene. Graphene is a 2-dimensional sheet of carbon one atom thick, and has been described as a wonder material as it is one of the thinnest, strongest materials so far discovered and conducts electricity more efficiently than copper. CNTs are being researched for their ability to act as nanocarriers, in order to deliver drugs or genes, for example to a tumor. Thickness of the blood brain barrier layer is approximately 500 nanometres. Supplied by Khuloud T. Al-Jamal, Houmam Kafa, Belen Ballesteros, Serene Tay & Michael Cicirko, courtesy of Wellcome Images.