Physics Nuclear Physics And Radiation Physics

Sensitive electrochemical immunoassay for 2,4,6-trinitrotoluene based on functionalized silica nanoparticle labels

Authors: Wang, Jun Liu, Guodong Wu, Hong Lin, Yuehe
 
Abstract: We present a poly(guanine)-functionalized silica nanoparticle (NP) label-based electrochemical immunoassay for sensitively detecting 2,4,6-trinitrotoluene (TNT). This immunoassay takes advantage of magnetic bead�based platform for competitive displacement immunoreactions and separation, and use electroactive nanoparticles as labels for signal amplification. For this assay, anti-TNT-coated magnetic beads interacted with TNT analog-conjugated poly(guanine)-silica NPs and formed analog-anti-TNT immunocomplexes on magnetic beads. The immunocomplexes coated magnetic beads were exposed to TNT samples, which resulted in displacing the analog conjugated poly(guanine) silica NPs into solution by TNT. In contrast, there are no guanine residues releasing into the solution in the absence of TNT. The reaction solution was then separated from the magnetic beads and transferred to the electrode surface for electrochemical measurements of guanine oxidation with Ru(bpy)32+ as mediator. The sensitivity of this TNT assay was greatly enhanced through dual signal amplifications: 1) a large amount of guanine residues on silica nanoparticles is introduced into the test solution by displacement immunoreactions and 2) a Ru(bpy)32+-induced guanine catalytic oxidation further enhances the electrochemical signal. Some experimental parameters for the nanoparticle label-based electrochemical immunoassay were studied and the performance of this assay was evaluated. The method is found to be very sensitive and the detection limit of this assay is ~ 0.1 ng mL-1 TNT. The electrochemical immunoassay based on the poly[guanine]-functionalized silica NP label offers a new approach for sensitive detection of explosives.
Publication Date: 03 Mar 2008
Report numbers: PNNL-SA-53440
DOE Contract number: AC05-76RL01830
Resource Type: Journal Article
Resource Relation: Journal: Analytica Chimica Acta, 610(1):112-118; Journal Volume: 610; Journal Issue: 1
Research Organizations: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Organizations: USDOE
Country of Publication: United States
Language: English
Keywords relating to this report:
DETECTION
ELECTROCHEMISTRY
GUANINE
IMMUNOASSAY
NANOSCIENCE AND NANOTECHNOLOGY
NANOSTRUCTURES
OXIDATION
PERFORMANCE
SENSITIVITY
SILICA
TNT

Subjects:
Related subjects:
ENVIRONMENTAL MOLECULAR SCIENCES LABORATORY
IMMUNOASSAY
NANOPARTICLES