Radioactive nanoparticle

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A radioactive nanoparticle is a nanoparticle that contains radioactive materials. Radioactive nanoparticles have applications in medical diagnostics, medical imaging, toxicokinetics, and environmental health, and are being investigated for applications in nuclear nanomedicine. Radioactive nanoparticles present special challenges in operational health physics and internal dosimetry that are not present for other substances, although existing radiation protection measures and hazard controls for nanoparticles generally apply.

Contents

Types and applications

Engineered

SPECT/CT images of injected gold-coated lanthanum/gadolinium phosphate nanoparticles containing the alpha-emitting radionuclide actinium-225 in a mouse. Depending on the surface functionalization, the particles migrate either to the lungs or the liver. SPECT-CT of radioactive nanoparticles in mouse.png
SPECT/CT images of injected gold-coated lanthanum/gadolinium phosphate nanoparticles containing the alpha-emitting radionuclide actinium-225 in a mouse. Depending on the surface functionalization, the particles migrate either to the lungs or the liver.

Engineered radioactive nanoparticles are used in medical imaging techniques such as positron emission tomography and single-photon emission computed tomography, [2] and an aerosol of carbon nanoparticles containing technetium-99m are used in a commercially available procedure for ventilation/perfusion scintigraphy of the lungs. [3] :122–125 Engineered radioactive nanoparticles are also used as a radiolabel to detect the presence of the nanoparticles themselves in environmental health and toxicokinetics studies. [3] :119–122

Engineered radioactive nanoparticles are being investigated for therapeutic use combining nuclear medicine with nanomedicine, especially for cancer. [3] :125–130 Neutron capture therapy is one such potential application. [2] [4] In addition, nanoparticles can help to sequester the toxic daughter nuclides of alpha emitters when used in radiotherapy. [1]

Nuclear imaging is non-invasive and has high sensitivity, and nanoparticles are useful as a platform for combining multiple copies of targeting vectors and effectors in order to selectively deliver radioisotopes to a specific region of interest. [5] Other benefits of nanoparticles for diagnostic and therapeutic use include increased blood and tumor retention time, as well as the possibility of using their unique physical and chemical properties in treatment.[ citation needed ] However, the nanoparticles must be engineered to avoid being recognized by the mononuclear phagocyte system and transported to the liver or spleen, often through manipulating their surface functionalization. [4] [5]

Targeting techniques include functionalizing radioactive nanoparticles with antibodies to target them to a specific tissue, and using magnetic nanoparticles that are attracted to a magnet placed over the tumor site. [4] Technetium-99m, indium-111, and iodine-131 are common radioisotopes used for these purposes, [3] :119–130 [4] with many others used as well. [6] [7] Radioactive nanoparticles can be produced by either synthesizing the nanoparticles directly from the radioactive materials, or by irradiating non-radioactive particles with neutrons or accelerated ions, sometimes in situ . [3] :119 [8]

Natural and incidental

As with all nanoparticles, radioactive nanoparticles can also be naturally occurring or incidentally produced as a byproduct of industrial processes. The main source of naturally occurring nanomaterials containing radionuclides is the decay of radon gas, whose immediate decay products are non-gaseous elements that precipitate into nanoscale particles along with atmospheric dust and vapors. Minor natural sources include primordial radionuclides present in the nanoscale portion of volcanic ash, and primordial and cosmogenic nuclides taken up by plants which are later burned. Radioactive nanoparticles may be incidentally produced by procedures in the nuclear industry such as nuclear reprocessing and the cutting of contaminated objects. [3] :16–20

Health and safety

Radioactive nanoparticles combine the hazards of radioactive materials with the hazards of nanomaterials. [3] :2–6 Inhalation exposure is the most common route of exposure to airborne particles in the workplace. Animal studies on some classes of nanoparticles indicate pulmonary effects including inflammation, granulomas, and pulmonary fibrosis, which were of similar or greater potency when compared with other known fibrogenic materials such as silica, asbestos, and ultrafine carbon black. Some studies in cells or animals have shown genotoxic or carcinogenic effects, or systemic cardiovascular effects from pulmonary exposure. [9] [10] The hazards of ionizing radiation depend on whether the exposure is acute or chronic, and includes effects like radiation-induced cancer and teratogenesis. [11] [12] In some cases, the inherent physicochemical toxicity of the nanoparticle itself may lead to lower exposure limits than those associated with the radioactivity alone, which is not the case with most radioactive materials. [3] :2–6

Radioactive nanoparticles present special challenges in operational health physics and internal dosimetry that are not present for other substances, as the nanoparticles' toxicokinetics depend on their physical and chemical properties including size, shape, and surface chemistry. For example, inhaled nanoparticles will deposit in different locations in the lungs, and will be metabolized and transported through the body differently, than vapors or larger particles. [3] :2–6 There may also be hazards from associated processes such as strong magnetic fields and cryogens used in imaging equipment, and handling of lab animals in experimental studies. [13] Effective risk assessment and communication is important, as both nanotechnology and radiation have unique considerations with public perception. [14]

Hazard controls

A fume hood is an engineering control typically used to protect workers using nanoparticles. Fume hood conventional.png
A fume hood is an engineering control typically used to protect workers using nanoparticles.

In general, most elements of a standard radiation protection program are applicable to radioactive nanomaterials, and many hazard controls for nanomaterials will be effective with the radioactive versions. The hierarchy of hazard controls encompasses a succession of five categories of control methods to reduce the risk of illness or injury. The two most effective are elimination and substitution, for example reducing dust exposure by eliminating a sonication process or substituting a nanomaterial slurry or suspension in a liquid solvent instead of a dry powder. Substitutions should consider both the radioactivity and physicochemical hazards of all the options, and also take into account that radioactive nanomaterials are easier to detect than non-radioactive substances. [3] :2–6, 35–41

Engineering controls should be the primary form of protection, including local exhaust systems such as fume hoods, gloveboxes, biosafety cabinets, and vented balance enclosures; radiation shielding; and access control systems. [3] :41–48 The need for negative room pressure to prevent contamination of outside areas can conflict with the customary use of positive pressure when pharmaceuticals are being handled, although this can be overcome through use of a cascade pressure system, or by handling nanomaterials in enclosures. [13]

Administrative controls include procedures to limit radiation doses, and contamination control procedures including encouraging good work practices and monitoring for contamination. Personal protective equipment is the least effective and should be used in conjunction with other hazard controls. In general, personal protective equipment intended for radioactive materials should be effective with radioactive nanomaterials, including impervious laboratory coats, goggles, safety gloves, and in some cases respirators, although the greater potential penetration through clothing and mobility in air of nanoparticles should be taken into account. [3] :48–63

See also

Related Research Articles

Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.

A radionuclide is an atom that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are powerful enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single element the decay rate, and thus the half-life (t1/2) for that collection, can be calculated from their measured decay constants. The range of the half-lives of radioactive atoms has no known limits and spans a time range of over 55 orders of magnitude.

Ionizing radiation Radiation that carries enough light energy to liberate electrons from atoms or molecules

Ionizing radiation is radiation, traveling as a particle or electromagnetic wave, that carries sufficient energy to detach electrons from atoms or molecules, thereby ionizing an atom or a molecule. Ionizing radiation is made up of energetic subatomic particles, ions or atoms moving at high speeds, and electromagnetic waves on the high-energy end of the electromagnetic spectrum.

Medical physics is, in general, the application of physics concepts, theories, and methods to medicine or healthcare. Medical physics departments may be found in hospitals or universities. Medical physics is generally split into two major subgroups, specifically radiation therapy and radiology. Medical physics of radiation therapy can involve work such as dosimetry, linac quality assurance, and brachytherapy. Medical physics of radiology involves medical imaging techniques such as magnetic resonance imaging, ultrasound, computed tomography, positron emission tomography, and x-ray.

Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.

Health physics

Health physics, also referred to as the science of radiation protection, is the profession devoted to protecting people and their environment from potential radiation hazards, while making it possible to enjoy the beneficial uses of radiation. Health physicists normally require a four-year bachelor’s degree and qualifying experience that demonstrates a professional knowledge of the theory and application of radiation protection principles and closely related sciences. Health physicists principally work at facilities where radionuclides or other sources of ionizing radiation are used or produced; these include research, industry, education, medical facilities, nuclear power, military, environmental protection, enforcement of government regulations, and decontamination and decommissioning—the combination of education and experience for health physicists depends on the specific field in which the health physicist is engaged.

Radioactive contamination US safety regulations for nuclear power and weapons

Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases, where their presence is unintended or undesirable.

Nanomaterials Materials whose granular size lies between 1 to 100 nm

Nanomaterials describe, in principle, materials of which a single unit small sized between 1 and 100 nm.

The impact of nanotechnology extends from its medical, ethical, mental, legal and environmental applications, to fields such as engineering, biology, chemistry, computing, materials science, and communications.

Nanotoxicology is the study of the toxicity of nanomaterials. Because of quantum size effects and large surface area to volume ratio, nanomaterials have unique properties compared with their larger counterparts that affect their toxicity. Of the possible hazards, inhalation exposure appears to present the most concern, with animal studies showing pulmonary effects such as inflammation, fibrosis, and carcinogenicity for some nanomaterials. Skin contact and ingestion exposure are also a concern.

Bioenvironmental Engineering

Bioenvironmental Engineering is a process of using engineering principles to reduce and solve environmental health risks and dangers caused by human activity It may comprise four general areas of work : radiation, industrial hygiene, environmental protection and emergency response.

Because of the ongoing controversy on the implications of nanotechnology, there is significant debate concerning whether nanotechnology or nanotechnology-based products merit special government regulation. This mainly relates to when to assess new substances prior to their release into the market, community and environment.

Radiation monitoring

Radiation monitoring involves the measurement of radiation dose or radionuclide contamination for reasons related to the assessment or control of exposure to radiation or radioactive substances, and the interpretation of the results.

Radiation dose reconstruction

Radiation dose reconstruction refers to the process of estimating radiation doses that were received by individuals or populations in the past as a result of particular exposure situations of concern. The basic principle of radiation dose reconstruction is to characterize the radiation environment to which individuals have been exposed using available information. In cases where radiation exposures can not be fully characterized based on available data, default values based on reasonable scientific assumptions can be used as substitutes. The extent to which the default values are used depends on the purpose of the reconstruction(s) being undertaken.

Engineering controls are strategies designed to protect workers from hazardous conditions by placing a barrier between the worker and the hazard or by removing a hazardous substance through air ventilation. Engineering controls involve a physical change to the workplace itself, rather than relying on workers' behavior or requiring workers to wear protective clothing.

The health and safety hazards of nanomaterials include the potential toxicity of various types of nanomaterials, as well as fire and dust explosion hazards. Because nanotechnology is a recent development, the health and safety effects of exposures to nanomaterials, and what levels of exposure may be acceptable, are subjects of ongoing research. Of the possible hazards, inhalation exposure appears to present the most concern, with animal studies showing pulmonary effects such as inflammation, fibrosis, and carcinogenicity for some nanomaterials. Skin contact and ingestion exposure, and dust explosion hazards, are also a concern.

Hazard substitution is a hazard control strategy in which a material or process is replaced with another that is less hazardous. Substitution is the second most effective of the five members of the hierarchy of hazard controls in protecting workers, after elimination. Substitution and elimination are most effective early in the design process, when they may be inexpensive and simple to implement, while for an existing process they may require major changes in equipment and procedures. The concept of prevention through design emphasizes integrating the more effective control methods such as elimination and substitution early in the design phase.

Engineering controls for nanomaterials

Engineering controls for nanomaterials are a set of hazard control methods and equipment for workers who interact with nanomaterials. Engineering controls are physical changes to the workplace that isolate workers from hazards, and are considered the most important set of methods for controlling the health and safety hazards of nanomaterials after systems and facilities have been designed.

Characterization of nanoparticles Measurement of physical and chemical properties of nanoparticles

The characterization of nanoparticles is a branch of nanometrology that deals with the characterization, or measurement, of the physical and chemical properties of nanoparticles. Nanoparticles measure less than 100 nanometers in at least one of their external dimensions, and are often engineered for their unique properties. Nanoparticles are unlike conventional chemicals in that their chemical composition and concentration are not sufficient metrics for a complete description, because they vary in other physical properties such as size, shape, surface properties, crystallinity, and dispersion state.

Titanium dioxide nanoparticle

Titanium dioxide nanoparticles, also called ultrafine titanium dioxide or nanocrystalline titanium dioxide or microcrystalline titanium dioxide, are particles of titanium dioxide (TiO2) with diameters less than 100 nm. Ultrafine TiO2 is used in sunscreens due to its ability to block UV radiation while remaining transparent on the skin. It is in rutile crystal structure and coated with silica or/and alumina to prevent photocatalytic phenomena. The health risks of ultrafine TiO2 from dermal exposure on intact skin are considered extremely low, and it is considered safer than other substances used for UV protection.

References

  1. 1 2 McLaughlin, Mark F.; Woodward, Jonathan; Boll, Rose A.; Wall, Jonathan S.; Rondinone, Adam J.; Kennel, Stephen J.; Mirzadeh, Saed; Robertson, J. David (2013-01-18). "Gold Coated Lanthanide Phosphate Nanoparticles for Targeted Alpha Generator Radiotherapy". PLOS ONE. 8 (1): e54531. Bibcode:2013PLoSO...854531M. doi:10.1371/journal.pone.0054531. ISSN   1932-6203. PMC   3548790 . PMID   23349921.
  2. 1 2 Prasad, Paras N. (2012-05-11). Introduction to Nanomedicine and Nanobioengineering. John Wiley & Sons. pp. 121–124. ISBN   9781118351079.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 "Radiation Safety Aspects of Nanotechnology". National Council on Radiation Protection and Measurements . 2017-03-02. Retrieved 2017-07-07.
  4. 1 2 3 4 Hamoudeh, Misara; Kamleh, Muhammad Anas; Diab, Roudayna; Fessi, Hatem (2008-09-15). "Radionuclides delivery systems for nuclear imaging and radiotherapy of cancer". Advanced Drug Delivery Reviews. 60 (12): 1329–1346. doi:10.1016/j.addr.2008.04.013. PMID   18562040.
  5. 1 2 Lewis, Michael R.; Kannan, Raghuraman (November 2014). "Development and applications of radioactive nanoparticles for imaging of biological systems". Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology. 6 (6): 628–640. doi:10.1002/wnan.1292. ISSN   1939-0041. PMID   25196269.
  6. ↑ Martín, Isabel García; Frigell, Jens; Llop, Jordi; Marradi, Marco (2016-03-22). "Radiolabelling of NPs Using Radiometals: 99mTc, 68Ga, 67Ga, 89Zr, and 64Cu". In Llop, Jordi; Gomez-Vallejo, Vanessa; Gibson, Peter Neil (eds.). Isotopes in Nanoparticles. Pan Stanford. pp. 183–229. doi:10.1201/b19950-9. ISBN   9789814669085.
  7. ↑ Llop, Jordi; Gómez-Vallejo, Vanessa; Martín, Isabel García; Marradi, Marco (2016-03-22). "Radiolabelling of Nanoparticles Using Radiohalogens, 13N, and 11C". In Llop, Jordi; Gomez-Vallejo, Vanessa; Gibson, Peter Neil (eds.). Isotopes in Nanoparticles. Pan Stanford. pp. 231–260. doi:10.1201/b19950-10. ISBN   9789814669085.
  8. ↑ Abbas, Kamel; Simonelli, Federica; Holzwarth, Uwe; Gibson, Peter (2009). "Overview on the production of radioactive nanoparticles for bioscience applications at the JRC Cyclotron – European Commission". Journal of Labelled Compounds and Radiopharmaceuticals. 52: S231–S255. doi:10.1002/jlcr.1643 . Retrieved 2017-07-11.
  9. ↑ "Current Intelligence Bulletin 65: Occupational Exposure to Carbon Nanotubes and Nanofibers". U.S. National Institute for Occupational Safety and Health : v–ix, 33–35. April 2013. doi:10.26616/NIOSHPUB2013145 . Retrieved 2017-04-26.
  10. ↑ "Current Intelligence Bulletin 63: Occupational Exposure to Titanium Dioxide". U.S. National Institute for Occupational Safety and Health: v–vii, 73–78. April 2011. doi:10.26616/NIOSHPUB2011160 . Retrieved 2017-04-27.
  11. ↑ "Radiation Health Effects". U.S. Environmental Protection Agency . 2017-05-23. Retrieved 2017-07-17.
  12. ↑ "Radiation and Its Health Effects". U.S. Nuclear Regulatory Commission . 2014-10-17. Retrieved 2017-07-17.
  13. 1 2 Reese, Torsten; Gómez-Vallejo, Vanessa; Ferreira, Paola; Llop, Jordi (2016-03-22). "Health and Safety Considerations for Radiolabelled Nanoparticles". In Llop, Jordi; Gomez-Vallejo, Vanessa; Gibson, Peter Neil (eds.). Isotopes in Nanoparticles. Pan Stanford. pp. 493–512. doi:10.1201/b19950-19. ISBN   9789814669085.
  14. ↑ Hoover, Mark D.; Myers, David S.; Cash, Leigh J.; Guilmette, Raymond A.; Kreyling, Wolfgang G.; Oberdörster, Günter; Smith, Rachel; Cassata, James R.; Boecker, Bruce B. (2015). "Application of an Informatics-Based Decision-Making Framework and Process to the Assessment of Radiation Safety in Nanotechnology". Health Physics. 108 (2): 179–194. doi:10.1097/hp.0000000000000250. PMID   25551501.
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