A Nanobody‐on‐Quantum Dot Displacement Assay for Rapid and Sensitive Quantification of the Epidermal Growth Factor Receptor (EGFR)

Biosensing approaches that combine small, engineered antibodies (nanobodies) with nanoparticles are often complicated. Here, we show that nanobodies with different C‐terminal tags can be efficiently attached to a range of the most widely used biocompatible semiconductor quantum dots (QDs). Direct im...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2022-08, Vol.61 (33), p.e202207797-n/a
Main Authors: Su, Ruifang, Wu, Yu‐Tang, Doulkeridou, Sofia, Qiu, Xue, Sørensen, Thomas Just, Susumu, Kimihiro, Medintz, Igor L., Bergen en Henegouwen, Paul M. P., Hildebrandt, Niko
Format: Article
Language:English
Subjects:
Antibodies
Biocompatibility
Biosensors
Chemical Sciences
Diagnostics
EGFRvIII
Energy transfer
Epidermal growth factor
Epidermal growth factor receptors
Fluorescence resonance energy transfer
FRET
Growth factors
Immunoassay
Lanthanides
Life Sciences
Nanobodies
Nanoparticles
Physics
Quantum dots
Receptors
Terbium
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Summary:Biosensing approaches that combine small, engineered antibodies (nanobodies) with nanoparticles are often complicated. Here, we show that nanobodies with different C‐terminal tags can be efficiently attached to a range of the most widely used biocompatible semiconductor quantum dots (QDs). Direct implementation into simplified assay formats was demonstrated by designing a rapid and wash‐free mix‐and‐measure immunoassay for the epidermal growth factor receptor (EGFR). Terbium complex (Tb)‐labeled hexahistidine‐tagged nanobodies were specifically displaced from QD surfaces via EGFR‐nanobody binding, leading to an EGFR concentration‐dependent decrease of the Tb‐to‐QD Förster resonance energy transfer (FRET) signal. The detection limit of 80±20 pM (16±4 ng mL−1) was 3‐fold lower than the clinical cut‐off concentration for soluble EGFR and up to 10‐fold lower compared to conventional sandwich FRET assays that required a pair of different nanobodies. Simple is powerful: Terbium complexes labeled with hexahistidine‐tagged nanobodies were displaced from quantum dots via EGFR‐nanobody binding. This simple concept resulted in a rapid and wash‐free single‐nanobody FRET immunoassay with picomolar limits of detection.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202207797