Studies on bioconjugation of quantum dots using capillary electrophoresis and fluorescence correlation spectroscopy

Abstract

In this paper, we systematically investigated the conjugation of quantum dots (QDs) with certain biomolecules using capillary electrophoresis (CE) and fluorescence correlation spectroscopy (FCS) methods. Commercial QDs and aqueous-synthesized QDs in our lab were used as labeling probes, certain bio-macromolecules, such as proteins, antibodies, and enzymes, were used as mode samples, and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysulfo-succinimide (Sulfo-NHS) were used as linking reagents. We studied the effects of certain factors such as the isoelectric points (pIs) of bio-macromolecules and buffer pH on the bioconjugation of QDs, and found that the pIs of bio-macromolecules played an important role in the conjugation reaction. By the optimization of the buffer pH some proteins with different pIs were efficiently conjugated with QDs using EDC and Sulfo-NHS as linking agents. Furthermore, we on-line investigated the kinetic process of QDs-bioconjugation by FCS and found that the conjugation reaction of QDs with protein was rapid and the reaction process almost completed within 10 min. We also observed that QDs conjugated with proteins were stable for at least 5 days in phosphate buffer. Our work described here will be very helpful for the improvement of the QDs conjugation efficiency in bioapplications.

Probing Antigen-Antibody Interaction Using Fluorescence Coupled Capillary Electrophoresis

“…CE-FL has been shown to be an effective method to detect QDs-protein interaction, which reveals subtle changes in the structure and composition of the surface bound ligands on QDs [21,30]. CE-FL can provide far more detailed information on QDs-protein assembly than ensemble fluorescence measurement [21].…”

An aptamer-based single particle method for sensitive detection of thrombin using fluorescent quantum dots as labeling probes

“…It was found that BPP values of QD-TBA were stable before and after the SEC separations, while BPP values were remarkably reduced with the increased ultrafiltration times. According to our previous experiment experiences [62] and the manufacture's suggestion, more than three repeated ultrafiltration operations were required in order to completely remove the unreacted aptamer. Herein, on comparison, SEC was more suitable for the purification of QD-TBA in our case.…”

CdTe quantum dots as fluorescent probes to study transferrin receptors in glioblastoma cells

“…Then, 1 mL of EDC (at 4 mg.mL -1 ) was added and after 5 min, 1 mL of Sulfo-NHS (at 5.5 mg.mL -1 ) was also added to the QDs aqueous suspension [21,22]. Then, 15 min later, 194 µL of Tf (at 1 mg.mL -1 ) was added to reach a ratio of QDs:Tf 1:2 (particle:molecule).…”