I read an amazing article about a new way to kill cancer cells a few hours ago.
I'm writing it up here so that I'll force myself to understand the mechanism well enough to explain it... Here's hoping I succeed.
Someday, maybe, this laser-ignited nano-death-star booby trap could kill bazillions of those nasties in people's bodies and save lives. For today, let me just try to tell you about how it's supposed to work. Perhaps you too will marvel at the ingenuity of various members of humankind of the subspecies homo scientificus.
First you figure out how to build a nanostar. Out of gold.
The nanoparticle is simple and cleverly designed. It is made of gold and shaped much like a star, with five to 10 points. (A nanostar is approximately 25 nanometers wide.)
Wouldn't it be easier to make it, say, spherical? Well probably, but it turns out you want as large a surface area as possible. Why?
The large surface area allows the researchers to load a high concentration of drug molecules onto the nanostar...
The drug used in the study is a single-stranded DNA aptamer (1) called AS1411. Approximately 1,000 of these strands are attached to each nanostar's surface.
This thing is really amazing. It is both the poison and the means to deliver itself. Like cyanide that auto-attaches itself to the king's server, then hops onto the king's plate once it nears the table.
((the aptamer)) is attracted to and binds to nucleolin, a protein overexpressed in cancer cells and found on the cell surface (as well as within the cell)... Bound to the nucleolin, the drug-loaded gold nanostars take advantage of the protein's role as a shuttle within the cell and hitchhike their way to the cell nucleus...
And when released from the nanostar, the DNA aptamer also acts as the drug itself.
So the thing attaches itself to a protein that occurs in high denisities in cancer cells and low densities elsewhere, hitches a ride on the back of the protein to the nucleus of the cell, and then -- zap!
Only it's even cooler (if more complicated) than that, because you need a real death ray to separate the drug from the nanostar once it's arrived.
The researchers then direct ultrafast pulses of light -- similar to that used in LASIK surgery -- at the cells. The pulsed light cleaves the bond attachments between the gold surface and the thiolated (2) DNA aptamers, which then can enter the nucleus.
Drug delivery and release is a difficult problem. But with this technique, three birds are killed with one stone:
-- large amounts of the drug can be loaded (because of the star shape).
-- transportation from the cell surface to the critical nuclear region is enabled.
-- once delivered, the nanostars serve as a target concentrating the light that will release the drug.
Does the process actually kill cancer cells? It seems promising:
Using electron microscopy, Odom and her team found their drug-loaded nanoparticles dramatically change the shape of the cancer cell nucleus. What begins as a nice, smooth ellipsoid becomes an uneven shape with deep folds. They also discovered that this change in shape after drug release was connected to cells dying and the cell population becoming less viable -- both positive outcomes when dealing with cancer cells.
The results are published in the journal ACS Nano.
... the researchers have gone on to study effects... on 12 other human cancer cell lines. The effect was much the same. "All cancer cells seem to respond similarly," Odom said. "This suggests that the shuttling capabilities of the nucleolin protein for functionalized nanoparticles could be a general strategy for nuclear-targeted drug delivery."
Today may not yet be that day, but someday we will have outsmarted these uncontrollably reproducing cells. Maybe with this technique. Maybe with another. Maybe with a "cocktail" approach. I just hope when that day comes we will have a health care system that is up to the task of mass-delivering to humans our long-sought-after and newly-won laser-focused nano-army of smart bombs.
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(1)
Aptamers are oligonucleic acid or peptide molecules that bind to a specific target molecule. Aptamers are usually created by selecting them from a large random sequence pool, but natural aptamers also exist in riboswitches. Aptamers can be used for both basic research and clinical purposes as macromolecular drugs. Aptamers can be combined with ribozymes to self-cleave in the presence of their target molecule. These compound molecules have additional research, industrial and clinical applications.
Yeah,
I had no idea either.
(2)
thiolated
(organic chemistry) reacted with, or converted into a thiol
thiol
(organic chemistry) a univalent organic radical (-SH) containing a sulphur and a hydrogen atom; a compound containing such a radical