Investigation of multivalent interactions between conjugate of quantum dots with c-Myc peptide tag and the anti-c-Myc antibody by capillary electrophoresis with fluorescence detection

Herein, we report an assay for detecting the binding of a multivalent peptide and antibody within a capillary with the use of fluorescence coupled capillary electrophoresis. Quantum dots and a c-Myc tag containing peptide EQKLISEEDLG₄ H₆ were injected sequentially and formed a multivalent quantum dot-EQKLISEEDLG₄ H₆ assembly within the capillary. The efficiency of the quantum dot-peptide self-assembly was affected by the peptide/quantum dot molar ratio, sampling time, and interval time. Finally, the binding of the monoclonal anti-c-Myc antibody and the multivalent quantum dot-EQKLISEEDLG₄ H₆ ligand was studied using an in-capillary assay. The microscopic dissociation constant for the self-assembly of monoclonal anti-c-Myc antibody and quantum dot-EQKLISEEDLG₄ H₆ was determined to be 14.1 μM with a stoichiometry of the peptide-antibody complex of 1.7 determined after fitting this to the Hill equation. This method can be further extended to detect a wide range of biomolecule-biomolecule binding interactions.