Double-enhancement strategy: A practical approach to a femto-molar level detection of prostate specific antigen-α 1-antichymotrypsin (PSA/ACT complex) for SPR immunosensing

Cuong Cao, Sang Jun Sim

Research output: Contribution to journalArticle

13 Citations (Scopus)


Prostate specific antigen-α1-antichymotrypsin was detected by a double-enhancement strategy involving the exploitation of both colloidal gold nanoparticles (AuNPs) and precipitation of an insoluble product formed by HRP-biocatalyzed oxidation. The AuNPs were synthesized and conjugated with horse-radish peroxidase-PSA polyclonal antibody by physisorption. Using the protein-colloid for SPR-based detection of the PSA/ACT complex showed their enhancement as being consistent with other previous studies with regard to AuNPs enhancement, while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the signal. The limit of detection was found at as low as 0.027 ng/ml of the PSA/ACT complex (or 300 fM), which is much higher than that of previous reports. This study indicates another way to enhance SPR measurement, and it is generally applicable to other SPR-based immunoassays.

Original languageEnglish
Pages (from-to)1031-1035
Number of pages5
JournalJournal of Microbiology and Biotechnology
Issue number6
Publication statusPublished - 2007 Jun 1
Externally publishedYes



  • Double enhancement
  • Enzyme precipitation
  • Gold nanoparticles
  • Oligo (ethylene glycol)
  • Prostate specific antigen-α-antichymotrypsin complex
  • Surface plasmon resonance

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology
  • Microbiology
  • Bioengineering

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