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

• DOI: 10.1002/anie.202207797
• Publication Date: 2022-06-27T15:29:02Z
• Authors: Ruifang Su; Yu‐Tang Wu; Sofia Doulkeridou; Xue Qiu; Thomas Just Sørensen; Kimihiro Susumu; Igor L. Medintz; Paul M. P. van Be...; Niko Hildebrandt
• Keywords: [PHYS]Physics [physics]; EGFRvIII; 0301 basic medicine; 0303 health sciences; [SDV]Life Sciences [q-bio]; General Chemistry; Single-Domain Antibodies; Catalysis; Communications; [PHYS] Physics [physics]; [SDV] Life Sciences [q-bio]; ErbB Receptors; 03 medical and health sciences; Lanthanides; [CHIM] Chemical Sciences; Quantum Dots; FRET; Fluorescence Resonance Energy Transfer; [CHIM]Chemical Sciences; Nanoparticles; Terbium; Diagnostics

AbstractBiosensing 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.