, Volume 396, Issue 3, pp 1345-1353
Date: 28 Nov 2009

Compatibility of quantum dots with immunobuffers, and its effect on signal/background of quantum dot-based immunoassay

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Abstract

In this work, the compatibility of quantum dots (QDs) with immunobuffers was studied by investigating the fluorescence stability of QDs in immunobuffers (in this research immunobuffers were defined as buffers for immunoaffinity binding or separation). Experimentally, the fluorescence signals of QDs with different surface chemistries (amine-terminated, streptavidin-coated, or antibody-conjugated) in commonly used immunobuffers were monitored versus time. The effect of some buffer composition on the compatibility of QDs with these buffers was also explored. Based on experimental data, the QD compatibility with these buffers is summarized, and it is found that a trace amount of bovine serum albumin added to most of these buffers helps QDs to achieve compatibility with them. Moreover, with QD as fluorescence label and C-reactive protein as a model analyte, a magnetic bead-based assay was performed using compatible and incompatible QD–immunobuffer systems. It is shown that compatible QD–immunobuffer systems can be used to achieve a higher assay signal/background ratio.

Figure

Fluorescence signals of streptavidin-coated QDs in 8 mol L−1 urea in PBS of pH 7.4 containing 1% SDS and 0.1% BSA vs. the measurement time (QD concentrations were 1 pmol L−1, 10 pmol L−1, 0.1 nmol L−1, and 1 nmol L−1, and there was 30 min vortex mixing between measurements)