Nanoscale Submarine Bot Delivers Drugs to Cells — Then Self Destructs

Dutch researchers have developed a medicine delivery system that propels itself through the cell walls of cancerous tumors.

Here at Seeker World Headquarters, actually a cluster of geosynchronous orbital modules above Antarctica, we like to keep a little light reading in the break room.

Now and again it pays off, and this morning we were thrilled to discover an intriguing item in the Dutch chemistry journal Angewandte Chemie. It seems scientists in the Netherlands have developed a nanoscopic submarine robot that delivers medicine by self-destructing inside cancer cells.

OK, we're making up the orbital thing. But the nanotech submarine is entirely real.

Researchers at Radboud University in the Netherlands began by assembling a synthetic nanoscale vesicle, a kind of bladder or sac that can be filled with liquids or gases — in this case, anti-cancer drugs. Vesicles are commonly produced by living cells, but can also be synthesized in the lab.

Similar nanomedical drug-delivery systems have been developed previously, but the Dutch technology adds some new twists. For one thing, the vesicle is self-propelling thanks to a chemical nanomotor that uses hydrogen peroxide for fuel. As the hydrogen peroxide degrades, the vesicle is propelled forward, into and through the cell wall of a cancerous tumor.

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As a self-propelling vehicle operating at the nano scale, the vesicle really does function like a fantastically tiny submarine. You can make a good case that the vesicle is a robot, too, depending on how you define your terms. Once the synthetic drug-delivery system gets within the vicinity of the cancer cells, it operates autonomously, reacting to specific chemical triggers that lead the vesicle to the tumor cells.

It gets even stranger: After the vesicle penetrates through the cell wall, it essentially self-destructs, releasing its payload of anti-cancer drugs where the medicine can do the most good.

This last bit proved to be the trickiest part. The Dutch team was trying to find a way for the vesicle to deliver the medicine within the bladder, but without the use of any outside trigger. That's when they came across a chemical signaling agent called glutathione, typically found in high concentrations within cancerous tumors.

By fiddling with the composition of the vesicle membrane, the Dutch team was able to seal the medicine itself with a material that reacts to the presence of glutathione. When the submarine penetrates through the cell wall, the glutathione dissolves the bonds that are more or less holding the entire submarine together.

"The glutathione enters into the shell of the nanomotor and then breaks down the redox-responsive disulfide bonds, resulting in cleavage of the outside shell," researchers explain in the study.

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The bottom line is that the new technique could potentially improve future “deliver-and-unpack” drug-delivery strategies, helping doctors get medicines precisely where they want them.

This is why it always pays to leaf through Dutch biochemistry journals.

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