Ring-shaped compounds better equip gold nanoparticles to fight cancer

Of the many weapons science has come to offer in the fight against cancer, ones that are showing plenty of potential are gold nanoparticles. We have seen how these could be grown inside tumors to tackle the problem from the inside, deliver drugs that do the job for them, or even explode to take out cancerous cells, but they aren’t without their problems. Scientists in Japan have found a solution to one of these drawbacks, finding that adding ring-shaped compounds to the mix can limit the buildup of clumps that otherwise inhibit their performance.

Conducted at Japan’s University of Hokkaido, the research focuses on the light-absorbing properties of gold nanoparticles, which is one of the ways they are able to kill off cancerous tissues. This capability can become compromised, however, when the gold nanoparticles start to clump together, a phenomenon that can be triggered by temperature, salt concentration and acidity.

Keeping the nanoparticles apart from one another is therefore a key focus for researchers in this field, and one method that has shown promise is coating them in polyethylene glycol (PEG), which stops gold surfaces clumping together to some degree, and is also biocompatible.

The researchers were investigating how applying the PEG in different ways could bring about different outcomes, and found particular success when covering them in a ring-shaped synthetic compound rather than a linear one. The “cyclic-PEG” attaches to the nanoparticles but doesn’t form chemical bonds with them, resulting in the coated particles staying dispersed rather than clumping together.

Illustration of conventional linear PEG-coated gold nanparticles (left) and cyclic PEG (right)
Illustration of conventional linear PEG-coated gold nanparticles (left) and cyclic PEG (right)

Yubo Wang, Takuya Yamamoto

The strength of this approach was demonstrated in mice where the cyclic-PEG was found to clear more slowly from the blood and buildup in greater numbers inside tumors compared to conventional PEG-coated particles. One limitation of the approach was that this accumulation of particles was lower than desired for a potent anti-cancer effect, but the researchers hope to address this shortcoming by fine-tuning the nanoparticle design in further work.

The research was published in the journal Nature Communications.

Source: Hokkaido University

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