Wiping Out Cancer With Gold

Why do some cancers come back, and what can we do about it?

Conventional cancer therapy involves a combination of surgery (manual excision of a cancerous tumour), chemotherapy (administration of anti-cancer drugs) and radiotherapy (the use of high-energy rays to kill cancer). However, sometimes, residual cancer cells can evade therapy and grow back into tumours, giving rise to cancer again. This is true especially after surgical excisions, where microscopic residual clusters are left behind. This condition is known as microscopic residual disease (MRD). While several diagnostic methods are available to detect residual cancer cells to avoid a possible recurrence, it is difficult to identify a small population of cancerous cells and selective elimination poses another challenge. Unfortunately, there’s not much we can do about it, at the moment.

The future, however, looks promising. Recently, researchers from the US and Belarus have come up with an innovative solution to this problem. In their study, they’ve developed a system where gold nanoparticles to target cancer cells and selectively destroy them. The procedure, called Plasmonic NanoBubble (PNB) nanosurgery, uses gold nanoparticles bound to antibodies selective for the cancer cell’s receptors. The cancer cells engulf these nanoparticles by a method called “receptor mediated endocytosis”, which basically means the intake of foreign material into the cell using surface receptors.

Once the nanoparticles are inside the cell, the nanoparticles are heated using infrared lasers (yes, lasers). The surrounding fluid in the cell vaporises, causing it to create a nanobubble that rapidly expands and collapses. Depending on the number of gold nanoparticle clusters in the cell, multiple nanobubble explosions eventually lead to cell death. While this happens on a scale too small to be optically measured, researchers could detect the procedure’s efficacy by measuring sound waves created by the micro-explosions. In the original study, mouse models with 3 to 30 residual cancer cells and MRD were treated with PNB nanosurgery, resulting in 100% tumour-free survival, and no local recurrence.

According to an article on Physics Central, this method is sensitive enough to selectively mark and destroy cancer cell clusters containing as few as three cancerous cells. This can be extremely beneficial for targeting and selectively eliminating microscopic clusters of cancer cells post-surgery.

As with any development in cancer therapy, there have been concerns regarding safety and selectivity. In an article published in Science, it has been mentioned that the procedure has been fine-tuned to enhance selectivity and avoid any damage to surrounding tissue. This has been achieved by two means: attaching an antibody to the gold nanoparticles to enhance selectivity and the use of ultrashort laser pulses to avoid collateral damage, as this avoids the heat from spreading to surrounding tissue.

PNB nanosurgery is going to undergo human trials in the next 2 years, and we’re all hoping that it passes the test.

As awesome as this sounds, what’s even more awesome (and so, so satisfying to watch) is a video of cancer cells exploding when hit by a laser pulse. Check out the following video, which describes the procedure in detail with snippets of exploding cells from the original study.

If you wish to, you can download a short (super-short) video of exploding cells from the original study by clicking here (DIE, CANCER, DIE!).

Do you have a question about cancer? Leave it in the comments below!

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