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Credit: Rhoda Baer
A novel type of nanocapsule can safely and effectively store isotopes that emit ionizing radiation, according to a paper published in Biochimica et Biophysica Acta.
In experiments, the nanocapsules were taken up by cells, accumulated near the perinuclear region, and persisted without degrading.
They also prevented nontargeted, radioactive daughter ions from escaping. These ions could cause significant damage if released, such as prompting the development of leukemia.
This research suggests the nanocapsules have the potential to advance radiation therapy, according to study author John M. Tomich, PhD, of Kansas State University’s Johnson Cancer Research Center.
Dr Tomich and his colleagues created the nanocapsules, called branched amphiphilic peptide capsules (BAPCs), by combining 2 related sequences of amino acids—bis(FLIVI)-K-KKKK and bis(FLIVIGSII)-K-KKKK.
“We found that the 2 sequences come together to form a thin membrane that assembled into little spheres, which we call capsules,” Dr Tomich said. “While other vesicles have been created from lipids, most are much less stable and break down. Ours are like stones, though. They’re incredibly stable and are not destroyed by cells in the body.”
The capsules’ ability to stay intact with the isotope inside and remain undetected by the body’s clearance systems prompted Dr Tomich to investigate using BAPCs for radiation therapies.
“The problem with current alpha-particle radiation therapies used to treat cancer is that they lead to the release of nontargeted, radioactive daughter ions into the body,” Dr Tomich said. “Radioactive atoms break down to form new atoms, called daughter ions, with the release of some form of energy or energetic particles. Alpha emitters give off an energetic particle that comes off at nearly the speed of light.”
The alpha particle destroys DNA and whatever vital cellular components are in its path. Similarly, the daughter ions recoil with high energy on ejection of the alpha particle. The daughter ions have enough energy to escape the targeting and containment molecules that are currently in use.
“Once freed, the daughter isotopes can end up in places you don’t want them, like bone marrow, which can then lead to leukemia and new challenges,” Dr Tomich said.
To see if the BAPCs could prevent the release of daughter isotopes, the researchers loaded the nanoparticles with 225Actinium. Upon decay, this compound releases 4 alpha particles and numerous daughter ions.
The team found that BAPCs loaded with the compound readily entered cells and migrated to a position alongside the nucleus.
As the alpha-particle-emitting isotopes decayed, the recoiled daughter ions collided with the capsule walls, essentially bouncing off them, and remained trapped inside the BAPCs. This completely blocked the release of the daughter ions, which prevented uptake in nontarget tissues.
Dr Tomich said more studies are needed to add target molecules to the surface of the BAPCs. But he believes the particles could provide a safer option for treating tumors with radiation therapy by reducing the amount of radioisotope required for killing cancer cells and reducing the side effects caused by off-target accumulation of radioisotopes.
“These capsules are easy to make and easy to work with,” Dr Tomich said. “I think we’re just scratching the surface of what we can do with them to improve human health and nanomaterials.” 
Credit: Rhoda Baer
A novel type of nanocapsule can safely and effectively store isotopes that emit ionizing radiation, according to a paper published in Biochimica et Biophysica Acta.
In experiments, the nanocapsules were taken up by cells, accumulated near the perinuclear region, and persisted without degrading.
They also prevented nontargeted, radioactive daughter ions from escaping. These ions could cause significant damage if released, such as prompting the development of leukemia.
This research suggests the nanocapsules have the potential to advance radiation therapy, according to study author John M. Tomich, PhD, of Kansas State University’s Johnson Cancer Research Center.
Dr Tomich and his colleagues created the nanocapsules, called branched amphiphilic peptide capsules (BAPCs), by combining 2 related sequences of amino acids—bis(FLIVI)-K-KKKK and bis(FLIVIGSII)-K-KKKK.
“We found that the 2 sequences come together to form a thin membrane that assembled into little spheres, which we call capsules,” Dr Tomich said. “While other vesicles have been created from lipids, most are much less stable and break down. Ours are like stones, though. They’re incredibly stable and are not destroyed by cells in the body.”
The capsules’ ability to stay intact with the isotope inside and remain undetected by the body’s clearance systems prompted Dr Tomich to investigate using BAPCs for radiation therapies.
“The problem with current alpha-particle radiation therapies used to treat cancer is that they lead to the release of nontargeted, radioactive daughter ions into the body,” Dr Tomich said. “Radioactive atoms break down to form new atoms, called daughter ions, with the release of some form of energy or energetic particles. Alpha emitters give off an energetic particle that comes off at nearly the speed of light.”
The alpha particle destroys DNA and whatever vital cellular components are in its path. Similarly, the daughter ions recoil with high energy on ejection of the alpha particle. The daughter ions have enough energy to escape the targeting and containment molecules that are currently in use.
“Once freed, the daughter isotopes can end up in places you don’t want them, like bone marrow, which can then lead to leukemia and new challenges,” Dr Tomich said.
To see if the BAPCs could prevent the release of daughter isotopes, the researchers loaded the nanoparticles with 225Actinium. Upon decay, this compound releases 4 alpha particles and numerous daughter ions.
The team found that BAPCs loaded with the compound readily entered cells and migrated to a position alongside the nucleus.
As the alpha-particle-emitting isotopes decayed, the recoiled daughter ions collided with the capsule walls, essentially bouncing off them, and remained trapped inside the BAPCs. This completely blocked the release of the daughter ions, which prevented uptake in nontarget tissues.
Dr Tomich said more studies are needed to add target molecules to the surface of the BAPCs. But he believes the particles could provide a safer option for treating tumors with radiation therapy by reducing the amount of radioisotope required for killing cancer cells and reducing the side effects caused by off-target accumulation of radioisotopes.
“These capsules are easy to make and easy to work with,” Dr Tomich said. “I think we’re just scratching the surface of what we can do with them to improve human health and nanomaterials.”
Credit: Rhoda Baer
A novel type of nanocapsule can safely and effectively store isotopes that emit ionizing radiation, according to a paper published in Biochimica et Biophysica Acta.
In experiments, the nanocapsules were taken up by cells, accumulated near the perinuclear region, and persisted without degrading.
They also prevented nontargeted, radioactive daughter ions from escaping. These ions could cause significant damage if released, such as prompting the development of leukemia.
This research suggests the nanocapsules have the potential to advance radiation therapy, according to study author John M. Tomich, PhD, of Kansas State University’s Johnson Cancer Research Center.
Dr Tomich and his colleagues created the nanocapsules, called branched amphiphilic peptide capsules (BAPCs), by combining 2 related sequences of amino acids—bis(FLIVI)-K-KKKK and bis(FLIVIGSII)-K-KKKK.
“We found that the 2 sequences come together to form a thin membrane that assembled into little spheres, which we call capsules,” Dr Tomich said. “While other vesicles have been created from lipids, most are much less stable and break down. Ours are like stones, though. They’re incredibly stable and are not destroyed by cells in the body.”
The capsules’ ability to stay intact with the isotope inside and remain undetected by the body’s clearance systems prompted Dr Tomich to investigate using BAPCs for radiation therapies.
“The problem with current alpha-particle radiation therapies used to treat cancer is that they lead to the release of nontargeted, radioactive daughter ions into the body,” Dr Tomich said. “Radioactive atoms break down to form new atoms, called daughter ions, with the release of some form of energy or energetic particles. Alpha emitters give off an energetic particle that comes off at nearly the speed of light.”
The alpha particle destroys DNA and whatever vital cellular components are in its path. Similarly, the daughter ions recoil with high energy on ejection of the alpha particle. The daughter ions have enough energy to escape the targeting and containment molecules that are currently in use.
“Once freed, the daughter isotopes can end up in places you don’t want them, like bone marrow, which can then lead to leukemia and new challenges,” Dr Tomich said.
To see if the BAPCs could prevent the release of daughter isotopes, the researchers loaded the nanoparticles with 225Actinium. Upon decay, this compound releases 4 alpha particles and numerous daughter ions.
The team found that BAPCs loaded with the compound readily entered cells and migrated to a position alongside the nucleus.
As the alpha-particle-emitting isotopes decayed, the recoiled daughter ions collided with the capsule walls, essentially bouncing off them, and remained trapped inside the BAPCs. This completely blocked the release of the daughter ions, which prevented uptake in nontarget tissues.
Dr Tomich said more studies are needed to add target molecules to the surface of the BAPCs. But he believes the particles could provide a safer option for treating tumors with radiation therapy by reducing the amount of radioisotope required for killing cancer cells and reducing the side effects caused by off-target accumulation of radioisotopes.
“These capsules are easy to make and easy to work with,” Dr Tomich said. “I think we’re just scratching the surface of what we can do with them to improve human health and nanomaterials.”