title: Investigation of magnetic nanoparticles for the rapid extraction and assay of alpha-emitting radionuclides from urine: demonstration of a novel radiobioassay method.
abstract: In the event of an accidental or intentional release of radionuclides into a populated area, massive numbers of people may require radiobioassay screening as triage for dose-reduction therapy or identification for longer-term follow-up. If the event released significant levels of beta- or alpha-emitting radionuclides, in vivo assays would be ineffective. Therefore, highly efficient and rapid analytical methods for radionuclide detection from submitted spot urine samples (≤50 mL) would be required. At present, the quantitative determination of alpha-emitting radionuclides from urine samples is highly labor intensive and requires significant time to prepare and analyze samples. Sorbent materials that provide effective collection and enable rapid assay could significantly streamline the radioanalytical process. The authors have demonstrated the use of magnetic nanoparticles as a novel method of extracting media for four alpha-emitting radionuclides of concern (polonium, radium, uranium and americium) from chemically-unmodified and pH-2 human urine. Herein, the initial experimental sorption results are presented along with a novel method that uses magnetic nanoparticles to extract radionuclides from unmodified human urine and then collect the magnetic field-induced particles for subsequent alpha-counting-source preparation. Additionally, a versatile human dose model is constructed that determines the detector count times required to estimate dose at specific protective-action thresholds. The model provides a means to assess a method's detection capabilities and uses fundamental health physics parameters and actual experimental data as core variables. The modeling shows that, with effective sorbent materials, rapid screening for alpha-emitters is possible with a 50-mL urine sample collected within 1 wk of exposure/intake.
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA 99352, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: O'Hara
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Carter
authors.forename: Jay A
authors.initials: JA
authors.lastname: MacLellan
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Warner
authors.forename: Marvin G
authors.initials: MG
authors.lastname: Warner
authors.forename: R Shane
authors.initials: RS
authors.lastname: Addleman
mesh_terms: D000512:Alpha Particles; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D011834:Radiation Monitoring / Q000295:instrumentation / Q000379:methods*; D011868:Radioisotopes / Q000652:urine*; D012680:Sensitivity and Specificity; D013997:Time Factors; D016482:Urinalysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D011868:Radioisotopes