Overlooked potential of positrons in cancer therapy

Hioki, Takanori; Gholami, Yaser Hadi; McKelvey, Kelly; Aslani, Alireza; Marquis, Harry; Eslick, Enid M.; Willowson, Kathy; Howell, Viive M.; Bailey, Dale L.

doi:10.1038/s41598-021-81910-4

Cited by 5 publications

(5 citation statements)

References 22 publications

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“…Similarly, proton bombardment on nitrogen targets can yield the positron emitters 13 N or 11 C via 14 N(p,pn) 13 N or 14 N(p,α) 11 C reactions 56 . While positron emitters, as opposed to alpha emitters, are generally useful for diagnostics using positron emission tomography, recent studies have proposed that positrons might also be useful for cancer therapy 57 . Whether nuclear reactions or other biological mechanisms under proton irradiation enhanced Ti- and N-containing materials more than under X-rays in our case should be investigated further.…”

Section: Resultsmentioning

confidence: 99%

Catalytic activity imperative for nanoparticle dose enhancement in photon and proton therapy

et al. 2022

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Nanoparticle-based radioenhancement is a promising strategy for extending the therapeutic ratio of radiotherapy. While (pre)clinical results are encouraging, sound mechanistic understanding of nanoparticle radioenhancement, especially the effects of nanomaterial selection and irradiation conditions, has yet to be achieved. Here, we investigate the radioenhancement mechanisms of selected metal oxide nanomaterials (including SiO2, TiO2, WO3 and HfO2), TiN and Au nanoparticles for radiotherapy utilizing photons (150 kVp and 6 MV) and 100 MeV protons. While Au nanoparticles show outstanding radioenhancement properties in kV irradiation settings, where the photoelectric effect is dominant, these properties are attenuated to baseline levels for clinically more relevant irradiation with MV photons and protons. In contrast, HfO2 nanoparticles retain some of their radioenhancement properties in MV photon and proton therapies. Interestingly, TiO2 nanoparticles, which have a comparatively low effective atomic number, show significant radioenhancement efficacies in all three irradiation settings, which can be attributed to the strong radiocatalytic activity of TiO2, leading to the formation of hydroxyl radicals, and nuclear interactions with protons. Taken together, our data enable the extraction of general design criteria for nanoparticle radioenhancers for different treatment modalities, paving the way to performance-optimized nanotherapeutics for precision radiotherapy.

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Section: Resultsmentioning

confidence: 99%

Catalytic activity imperative for nanoparticle dose enhancement in photon and proton therapy

et al. 2022

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“…As far as the pick-off lifetimes are concerned, those huge differences are not very important because the core contribution does not exceed ≈15% in scheme II, being much smaller in scheme III. Nevertheless, the Auger decays initiated by core annihilation events enhance the probability of lethal DNA damage, which would make positron-based cancer treatments more efficient than the electron-based counterparts . Our results point out that core annihilation lifetimes are even more challenging to theory than the pick-off ones.…”

Section: Resultsmentioning

confidence: 99%

“…We calculate two-photon annihilation rates to illustrate how the contributions from the direct and pick-off mechanisms can be easily obtained from the electronic and positronic molecular orbitals. Motivated by the potential relevance of the annihilation with core electrons to positron-based cancer treatments, we also decompose the pick-off rates into the contributions from valence and core electrons.…”

Section: Methodsmentioning

confidence: 99%

“…PALS is now acknowledged as a useful tool to investigate the conformational, structural, and microenvironmental properties of biomimetic systems as well as phase transitions of lipid bilayers and pharmaceutically relevant compounds. , Positron emission tomography (PET) has also become a well-established imaging technique of living tissues, − and the Ps contribution to the annihilation signals is expected to provide a basis for further technological progress. For instance, the sensitivity of ortho-Ps lifetime to the concentration of molecular oxygen could probe the hypoxic regions in tumors, , and three-photon detection could determine the location of ortho-Ps annihilation in the tissue with improved accuracy. , Finally, positrons and Ps atoms are produced along the tracks of the heavy particles used in ion-beam cancer therapy, , and positron-based tumor treatments have also been proposed. , …”

Section: Introductionmentioning

confidence: 99%

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Multicomponent Quantum Mechanics/Molecular Mechanics Study of Hydrated Positronium

et al. 2022

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We propose a model for solvated positronium (Ps) atoms in water, based on the sequential quantum mechanics/molecular mechanics (s-QM/MM) protocol. We developed a Lennard-Jones force field to account for Ps–water interactions in the MM step. The repulsive term was obtained from a previously reported model for the solvated electron, while the dispersion constant was derived from the Slater–Kirkwood formula. The force field was employed in classical Monte Carlo (MC) simulations to generate Ps–solvent configurations in the NpT ensemble, while the quantum properties were computed with the any-particle molecular orbital method in the subsequent QM step. Our approach is general, as it can be applied to other liquids and materials. One basically needs to describe the solvated electron in the environment of interest to obtain the Ps solvation model. The thermodynamical properties computed from the MC simulations point out similarities between the solvation of Ps and noble gas atoms, hydrophobic solutes that form clathrate structures. We performed convergence tests for the QM step, with particular attention to the choice of basis set and expansion centers for the positronic and electronic subsystems. Our largest model was composed of the Ps atom and 22 water molecules in the QM region, corresponding to the first solvation shell, surrounded by 128 molecules described as point charges. The mean electronic and positronic vertical detachment energies were (4.73 ± 0.04) eV and (5.33 ± 0.04) eV, respectively. The latter estimates were computed with Koopmans’ theorem corrected by second-order self-energies, for a set of statistically uncorrelated MC configurations. While the Hartree–Fock wave functions do not properly account for the annihilation rates, they were useful for numerical tests, pointing out that annihilation is more sensitive to the choice of basis sets and expansion centers than the detachment energies. We further explored a model with reduced solute cavity size by changing the Ps–solvent force field. Although the pick-off annihilation lifetimes were affected by the cavity size, essentially the same conclusions were drawn from both models.

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“…A positron is a positively charged electron and when emitted from the nucleus, can deposit a high amount of penetrating radiation in a relatively small volume although with lower ionization potential. Thus, it can be considered a therapeutic radiopharmaceutical and has been studied on prostate cancer cell line and has been found to show therapeutic effect [126] .…”

Section: Other Tumors/therapiesmentioning

confidence: 99%

Current and upcoming radionuclide therapies in the direction of precision oncology: A narrative review

Shah

Ruppell

Bokhari

et al. 2023

European Journal of Radiology Open

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Overlooked potential of positrons in cancer therapy

Cited by 5 publications

References 22 publications

Catalytic activity imperative for nanoparticle dose enhancement in photon and proton therapy

Catalytic activity imperative for nanoparticle dose enhancement in photon and proton therapy

Multicomponent Quantum Mechanics/Molecular Mechanics Study of Hydrated Positronium

Current and upcoming radionuclide therapies in the direction of precision oncology: A narrative review

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