Hybrid Nanoparticle Platform for Nanoscale Scintillation Proximity Assay

Colleen M. Janczak, Isen A.C. Calderon, Eka Noviana, Priyanka Hadvani, Joo Ryung Lee, Craig A. Aspinwall

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


β-Particle emitting radionuclides, such as 3H, 14C, 32P, 33P, and 35S, are important molecular labels due to their small size and the prevalence of these atoms in biomolecules but are challenging to selectively detect and quantify within aqueous biological samples and systems. Here, we present a core-shell nanoparticle-based scintillation proximity assay platform (nanoSPA) for the separation-free, selective detection of radiolabeled analytes. nanoSPA is prepared by incorporating scintillant fluorophores into polystyrene core particles and encapsulating the scintillant-doped cores within functionalized silica shells. The functionalized surface enables covalent attachment of specific binding moieties such as small molecules, proteins, or DNA that can be used for analyte-specific detection. nanoSPA was demonstrated for detection of 3H-labeled analytes, the most difficult biologically relevant β-emitter to measure due to the low energy β-particle emission, using three model assays that represent covalent and noncovalent binding systems that necessitate selectivity over competing 3H-labeled species. In each model, nmol quantities of target were detected directly in aqueous solution without separation from unbound 3H-labeled analyte. The nanoSPA platform facilitated measurement of 3H-labeled analytes directly in bulk aqueous samples without surfactants or other agents used to aid particle dispersal. Selectivity for bound 3H-analytes over unbound 3H analytes was enhanced up to 30-fold when the labeled species was covalently bound to nanoSPA, and 4- and 8-fold for two noncovalent binding assays using nanoSPA. The small size and enhanced selectivity of nanoSPA should enable new applications compared to the commonly used microSPA platform, including the potential for separation-free, analyte-specific cellular or intracellular detection.

Original languageEnglish (US)
Pages (from-to)1259-1266
Number of pages8
JournalACS Applied Nano Materials
Issue number3
StatePublished - Mar 22 2019


  • composite nanomaterial
  • core-shell nanoparticle
  • radioisotope
  • scintillation proximity assay
  • β-emission

ASJC Scopus subject areas

  • General Materials Science


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