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Morphing Atoms May Lead to New Cancer Therapies

August 05, 2015

Morphing atoms for cancer research

Call it modern day alchemy. A research team led by Professor E. Charles H. Sykes of Tufts University recently documented an historical first: they actually witnessed the transformation of a single atom of one element morphing into a completely different element. While that feat is a major scientific accomplishment in itself, it is what the researchers learned while observing this transformation that could well lead to revolutionary new cancer therapies.1

Making History…Again

The Sykes lab is no stranger to making scientific headlines. In 2011, they earned global recognition and a place in the Guinness Book of World Records for creating the world’s smallest single-molecule motor.2

This time around, the Sykes lab is celebrating an even more elusive achievement that has evaded researchers since the beginnings of science. From Plato to Isaac Newton, thousands of chemists through the centuries have experimented with metals in hopes of changing one substance into another… usually gold or the elixir of life.3

While gold does play an important role in the Sykes lab’s achievement, it is not because the team found a way to create the precious metal. Rather, gold-coated mica served as a base upon which collaborating scientists from PerkinElmer placed a droplet of water infused with radioactive isotope Iodine-125 (125I). When the water evaporated, it created a monolayer of iodine atoms that attached themselves to the thin sheet of gold. The 125I samples were then placed into a PerkinElmer NENSure Packaging System made especially for radionuclides and safely shipped to Tufts.4

After carefully preparing the lab and staff to receive the 125I samples, Sykes’s team then observed the radioactive atoms through a low-temperature scanning tunneling microscope – one of only a handful of such instruments in the U.S. The special instrument enables researchers to examine surfaces at atomic levels.1 Over a period of several weeks, the team could see individual atoms actually decaying. After recording images of the process, the Tufts scientists employed an X-ray photoelectron spectrometer to verify the chemical transmutation occurring in the samples, and then enlisted the help of researchers from University College London to verify what they saw. All agreed that each iodine atom had a proton in its nucleus change into a neutron as it decayed, and became 125tellurium, a non-radioactive isotope of the element tellurium. “By taking the measurement every week or two, we could see the chemical transmutation from one element to another,” Sykes says.5 Once again, his lab found itself knocking on history’s door.6

A Serendipitous Discovery

Tufts observation of 125I’s transformation into another element is a major scientific achievement. But a more surprising discovery soon followed.

“The big discovery came when we measured what was happening during the nuclear transformation,” Sykes says. During that morphing process, 125I emits gamma rays and electrons, and the sub-atomic particles are carried off, leaving a very stable material.

“When we measured the lower-energy electrons emitted from the decay process, which have never been measured before, there was a big increase in their flux compared to what had been predicted theoretically,” Sykes says. “These are the electrons of interest for cancer therapies because they break DNA strands apart without killing neighboring cells.”

Further research found that the transforming material was not only very stable, it emitted six times as many low-energy electrons as regular 125I, says George Pappas, Operations Director at PerkinElmer’s Health Sciences facility in North Billerica, MA, who, along with Garth Brown, PerkinElmer’s Senior Iodinator, collaborated on the project. “The gold acts as a reflector, which promotes the big increase in low-energy electrons.”

“We didn’t expect this going in, but as we saw it happening, we measured it, and we also understood what and why it was happening,” Sykes says. “Because it was more stable than we expected, we realized it fell within the acceptable parameters and energy range for cancer therapies. That could eventually have clinicians rethink how they currently use radioactive isotopes and instead attach them to gold nanoparticles for cancer remediation in the future.”

The Future Is Now

For scientists such as Sykes and Pappas, both are anxious to move the 125I findings to the next level. “Currently, cancer treatments using 125I seeds have up to an 85% success rate for prostate cancer,” Pappas says. “This number could grow even higher with new therapies using the morphed iodine.”

Prof. Sykes says that the gold-based 125I nanoparticles can theoretically attach themselves to tumors, destroying them from within. Healthy tissue and organs nearby remain unaffected, since the low energy electrons don’t go very far and the nanomaterial would eventually be flushed out of the system. Presently, Sykes says, 125I pellets are encased in titanium capsules, which inhibit the radiation, making these treatments less effective.

If proven right, the Sykes lab is on the brink of its biggest discovery yet. The team is already investigating how its transformed radioisotope affects DNA and travels through biological fluids. In addition, Prof. Sykes and Pappas are already discussing a repeat observation, only this time using 131Iodine, which emits seven times more energy than 125I, but has a shorter half-life of only eight days.

“Our discovery has great promise for improving cancer therapies,” Sykes says, and Pappas agrees. “We are happy to be a part of this in advancing Tufts’ use of radioactive materials,” he says, then paused a moment. “It’s exciting to see history being made.”

References

  1. Single-Molecule Surface Chemistry, E. Charles H. Sykes, Chemistry Department, Tufts University.
  2. Electric motor made from a single molecule, BBC News.
  3. Isaac Newton – Newton the Alchemist, Alchemy Lab.
  4. Pappas, George, “Iodine Used in Tufts Collaboration,” email, 2015.
  5. Scientists Are First to See Elements Transform at Atomic Scale, Tufts Now.
  6. Witness to chemical alchemy: elements transform at atomic scale, R&D.

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