New nanoparticles may help stop tumour growth

Using nanoparticles of the main ingredient in common antacid tablets can help prevent a cancerous tumour from growing, researchers including those of Indian-origin have claimed.
For the first time, researchers from Washington University in St Louis have modulated pH in solid tumours using intentionally designed nanoparticles.
Researchers used two novel methods to create nanoparticles from calcium carbonate that were injected intravenously into a mouse model to treat solid tumours.
The compound changed the pH of the tumour environment, from acidic to more alkaline, and kept the cancer from growing.
"Cancer kills because of metastasis. The pH of a tumour has been heavily correlated with metastasis," said Avik Som from Washington University who led the study.

"For a cancer cell to get out of the extracellular matrix, or the cells around it, one of the methods it uses is a decreased pH," he added.

In water, the pH in calcium carbonate increases as high as 9. But when injected into the body, researchers discovered that calcium carbonate only raises the pH to 7.4, the normal pH in the human body.
However, working with calcium carbonate presented some challenges, according to researchers including Ramesh Raliya, Pratim Biswas and Srikanth Singamaneni.
"Calcium carbonate does not like to be small. Calcium carbonate crystals are normally 10 to 1,000 times bigger than an ideal nanoparticle for cancer therapy," said Som.

"On top of that, calcium carbonate in water will constantly try to grow, like stalactites and stalagmites in a cave," he added.
Researchers developed two methods to solve this issue - one using polyethyleneglycol-based diffusion to synthesise 20- and 300-nanometre-sized calcium carbonate and the other to create 100-nanometre-sized calcium carbonate by building on a method known as ethanol-assisted diffusion.
By harnessing the complementary expertise of the different labs, researchers developed a solvent made of albumin to keep the calcium carbonate nanoparticles from growing, allowing them to be injected into the body intravenously.
Researchers injected the calcium carbonate nanoparticles into the mouse fibrosarcoma model daily, which kept the tumour from growing. However, when they stopped injecting the nanoparticles, it started growing again.

The findings were published in the journal Nanoscale.