Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media

Colleen M. Janczak, Isen A.C. Calderon, Zeinab Mokhtari, Craig A Aspinwall

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3H, 35S, and 33P, important biological isotopes, is challenging due to the low energies (Emax ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3H, 35S, and 33P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3H, 8 nCi/mL for 35S, and <1 nCi/mL for 33P.

Original languageEnglish (US)
Pages (from-to)4953-4960
Number of pages8
JournalACS Applied Materials and Interfaces
Volume10
Issue number5
DOIs
StatePublished - Jan 1 2018

Fingerprint

Polystyrenes
Scintillation
Radioisotopes
Silicon Dioxide
Silica
Nanoparticles
Fluorophores
Liquids
Biomolecules
Biological systems
Time measurement
Surface-Active Agents
Isotopes
Phosphors
Organic solvents
Labels
Polymers
Surface active agents
Photons
Wavelength

Keywords

  • composite nanoparticle
  • core-shell nanoparticle
  • radioisotope
  • scintillation
  • β-emission

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media. / Janczak, Colleen M.; Calderon, Isen A.C.; Mokhtari, Zeinab; Aspinwall, Craig A.

In: ACS Applied Materials and Interfaces, Vol. 10, No. 5, 01.01.2018, p. 4953-4960.

Research output: Contribution to journalArticle

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AB - β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3H, 35S, and 33P, important biological isotopes, is challenging due to the low energies (Emax ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3H, 35S, and 33P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3H, 8 nCi/mL for 35S, and <1 nCi/mL for 33P.

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