NSTI Nanotech 2009

Rapid and Label-free Protein Biomarker Detection based on Quantum Dot-Aptamer-Intercalating Dye Nanoconjugates

Y-H Lao, Y-S Li, C-W Chi, L-C Chen
Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, TW

Keywords: quantum dot, aptamer, intercalating dye, biomarkers, protein detection


In this work, we present a novel quantum dot (QD)-aptamer-intercalating dye nanoconjugate reagent for rapid and label-free protein biomarker detection to meet the increasing need of on-site diagnostics. To construct the nanoconjugate reagent, aptamer probes are anchored on quantum dots at first. Then intercalating dyes are stained to the double helical region of the aptamer probes. Accordingly, fluorescence resonance energy transfer (FRET) between intercalating dyes and QDs can be observed when the nanoconjugates are constructed. When recognizing target proteins, aptamer probes on QDs undergo binding-induced folding and conformational changes. Consequently, intercalating dyes are released from the nanoconjugates, and the FRET signal is suppressed. The concentrations of a protein biomarker can be thus correlated to the extent of FRET signal suppression. Detection of human thrombin is demonstrated by this method. The detection limit of thrombin is lower than 195 pM where the signal-to-noise ratio is 13.3. This system also demonstrates the high specificity of such a nanoconjugate-based protein assay. The thrombin-specific nanoconjugate does not crosstalk with bovine serum album and serum total protein. Furthermore, the detection is label-free and compatible with multiplex serum biomarker detection which will be presented in the symposium.
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