Grave type material could stimulate protonotherapy

A new touch on pencil graphite could be a key ingredient for better the treatment of cancer, according to Singapore scientists. The graphite consists of layers stacked with graphene, a sheet of carbon atoms with unique atoms arranged in repeated hexagonal rings. Now add the pentagons, the heptagons and the octagues of the carbon atoms in the sheet, and you look at a new form of ultra-light carbon which promises to refine the bundles of subatomic particles used in protonotherapy.

Ultramine carbon materials leaves have been used for decades in protonotherapy to filter particles in high precision beams intended to kill tumors. But, they take time to manufacture and often contain impurities in the manufacturing process which lower the precision of the beam. In research described in Nanotechnology of nature, Jiong Lu and his colleagues at the National University of Singapore and in China have developed a technique that can develop a 200-millimeter sheet of a new type of ultra-recent carbon material in just 3 seconds, without detectable impurities.

Protonotherapy is non -invasive radiotherapy in which hydrogen ions are accelerated through a cyclotron to form a high energy beam used to destroy DNA in tumors. In a cyclotron, an electromagnetic field accelerates molecular hydrogen ions, which spiral outwards when they pick up the speed. They then strike a carbon sheet which eliminates the electrons from hydrogen, leaving protons that come out of the machine as a high energy beam. Protonotherapy is often preferred as treatment due to its precision. The sharp beam eliminates tumors while preserving healthy tissues. The new carbon promises an even sharper and more intense beam, which makes treatment more powerful.

The advantages of the new material, called an ultra-cleaning monocouche amorphous carbon (UC-MAC), are derived from its disorderly annular structure, which contrasts with the perfect hexagon rings in the graphene. The structures present in UC-Mac create tiny pores in the material which is only a tenth of a large nanometer. The researchers found a way to refine these pores on an Angstrom scale to control how the filter material the hydrogen ions, in order to produce proton beams with less diffusion.

Nanograins and nanopores

The new technique begins with the deposit of a thin copper film on a sapphire brochure inside a room filled with high density plasma. Depending on the temperature of the copper and the speed at which it is deposited, irregular crystals of a few tens of nanometers called nanograins form. Nanograins provide the right conditions for UC-Mac to develop, and finally, a complete layer of the carbon material of atom crystallizes above the copper. This growth occurs in just three seconds, more than a faster order of magnitude than the previous methods used to grow carbon sheets.

Huii Lin, a scientific researcher from the Singapore agency for science, technology and research that worked on the project, explains that the rapid synthesis speeds come from the high density of nanograins which are formed on copper, and plasma in the growth chamber, which provides high quantities of particles which react with the substrate to form the carbon structure.

Despite its potential importance in cancer treatment, Lin says that UC-Mac was originally designed with different applications in mind. “We tried it in electronics and optical devices, and after three years of work, we discovered its unique advantage as a membrane to produce precision proton bundles,” he explains.

Due to Angstrom size pores in the material, the team discovered that UC-Mac was only suitable for transforming molecular hydrogen ions into protons. The acceleration of molecular hydrogen ions through the cyclotron instead of already filtered protons has increased the amount of protons in the beam in a given time, of an order of magnitude.

Lin thinks that it will always take time for the equipment to be the marketing point. He explains that, like many other 2D materials, “you need dozens of steps” to grow carbon on the substrate. Thus, simplifying the process is crucial to get closer to marketing. Finally, the material can make protonotherapy a more widely available treatment option. “The UC-Mac makes the proton beams more adjustable [and] affordable, ”explains Lin.