Abstract
Colloidal gold nanoparticles (AuNPs) and precipitation of an insoluble product formed by HRP-biocatalyzed oxidation of 3,3′-diaminobenzidine (DAB) in the presence of H2O2 were used to enhance the signal obtained from the surface plasmon resonance (SPR) biosensor. The AuNPs were synthesized and functionalized with HS-OEG3-COOH by self assembling technique. Thereafter, the HS-OEG3-COOH functionalized nanoparticles were covalently conjugated with horseradish peroxidase (HRP) and anti IgG antibody to form an enzyme-immunogold complex. Characterizations were performed by several methods: UV-vis absorption, DLS, HR-TEM and FT-IR. The Au-anti IgG-HRP complex has been applied in enhancement of SPR immunoassay using a sensor chip constructed by 1:9 molar ratio of HS-OEG6-COOH and HS-OEG3-OH for detection of anti-GAD antibody. As a result, AuNPs showed their enhancement as being consistent with other previous studies while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the SPR detection. The limit of detection was found as low as 0.03 ng/ml of anti-GAD antibody (or 200 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 language | English |
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Pages (from-to) | 1874-1880 |
Number of pages | 7 |
Journal | Biosensors and Bioelectronics |
Volume | 22 |
Issue number | 9-10 |
DOIs | |
Publication status | Published - 2007 Apr 15 |
Externally published | Yes |
Keywords
- Anti-GAD antibody
- Enhancement
- Enzyme precipitation
- Gold nanoparticles
- Oligo(ethylene glycol)
- Surface plasmon resonance
ASJC Scopus subject areas
- Biotechnology
- Biophysics
- Biomedical Engineering
- Electrochemistry