Ultrasensitive protein detection in blood serum using gold nanoparticle probes by single molecule spectroscopy

Jiji Chen, Chungang Wang, Joseph Irudayaraj

Research output: Contribution to journalArticlepeer-review


A one-step rapid and ultrasensitive immunoassay capable of detecting proteins in blood serum is developed using gold nanoprobes and fluorescence correlation spectroscopy (FCS). In this approach we take advantage of the inherent photoluminescence property of gold nanoparticles (GNPs) to develop a fluorophore-free assay to observe binding entities by monitoring the diffusion of bound versus unbound molecules in a limited confocal volume. 40-nm GNPs conjugated separately with rabbit anti-IgG (Fc) and goat anti-IgG (Fab) when incubated in blood serum containing IgG forms a sandwich structure constituting dimers and oligomers that can be differentiated by to detect IgG in blood serum at a limit of detection (LOD) of 5pg/ml. The novelty of integrating GNPs with FCS to develop a sensitive blood immunoassay brings single molecule methods one step closer to the clinic.

Original languageEnglish (US)
Article number040501
JournalJournal of biomedical optics
Issue number4
StatePublished - 2009
Externally publishedYes


  • blood serum
  • detection
  • fluorescence correlation spectroscopy
  • gold nanoparticles

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering


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