Scientists have taken a step towards understanding the way plasma beams can kill cancer cells, potentially leading to the development of new therapies for the killer disease.

Treatment by plasma beam – highly energetic particles with positive and negative charges – has some advantages over other treatments, for example it is free of the side effects that go with radiotherapy and is more precise than laser treatments.

However a major obstacle to its use in clinical applications has been a lack of understanding of the underlying mechanism: were the cancer cells killed by physical forces such as heat, ultraviolet radiation and charged particles generated by the plasma, or “poisoned” by chemicals created in reactions with the plasma, such as hydrogen peroxide, ozone and nitrate ions?

Some current plasma guns vaporize cancer cells with power, but new research by a team led by XIA Weidong of the University of Science and Technology of China and Paul K. Chu of the department of Physics and Materials Science at City University of Hong Kong has shown that this approach may not always be necessary.

In a paper in the latest issue of the journal Scientific Reports, the researchers found a relatively gentle plasma beam could in some cases cause enough chemical reactions in a cancer cell to kill it.

They put water under plasma radiation for some time until it contained chemicals generated by the plasma, including ozone and nitrate ions, and then observed the action of the water on a common protein known as lactate dehydrogenase enzyme.

They found the result was almost the same as putting the protein directly under a plasma beam.

"That means, at least in some circumstances, the effects of plasma treatment could be achieved without heat, UV radiation and charged particles,” Chu said.

The plasma-induced chemicals first modified some important amino acids and caused structural changes in the protein molecule, which lost its recognition and catalytic functions. The chemicals also hampered catalytic reactions between the molecules, which would eventually lead to the death of the cell.

"Uncovering the mechanism of plasma treatment is important. Only when we fully understand how it works and what exactly happens in the process could we use the technology properly and exploit its advantages to the limit,” Chu said.

He said the team is exploring other applications, such as artificial bone materials with surfaces treated by plasma for superior anti-infection ability and biocompatibility. (South China Morning Post)