Electrophoretic study of peptide‐mediated quantum dot‐human immunoglobulin bioconjugation

Abstract

The bioconjugation of quantum dots (QDs) is a key process in their application for bioanalysis as well as imaging. The coupling of QDs with biologically active molecules such as peptides, nucleic acids, and/or antibodies enables their fluorescent labeling, and therefore, selective and sensitive tracking during the bioanalytical process, however, the efficiency of the labeling and preservation of the biological activity of the bioconjugate have to be considered. In this study, a new approach of the bioconjugation of CdTe-QDs and human immunoglobulin employing a small peptide is described. The heptapeptide (HWRGWVC) was synthesized and characterized by mass spectrometry, liquid chromatography, and capillary electrophoresis. Moreover, the peptide was used as a capping agent for QDs synthesis. The CdTe-QDs were synthesized by microwave synthesis (600 W, 20 min) using 3.2 mM CdCl2 and 0.8 mM Na2TeO3. The bioconjugation of QDs capped by this peptide with immunoglobulin was investigated by capillary electrophoresis and magnetic immunoextraction coupled with electrochemical detection by differential pulse voltammetry. Furthermore, the applicability of prepared bioconjugates for fluorescent immunodetection was verified using immobilized goat antihuman IgG antibody.

Characterization and separation of semiconductor quantum dots and their conjugates by capillary electrophoresis

“…Similar report could be found in other research group . Recently, Janu et al presented a new approach for the bioconjugation of CdTe QDs and human IgG, where heptapeptide was employed as a capping agent for QDs synthesis . CE with LIF and UV detection was applied for investigating the bioconjugation with QDs.…”

Dual-color immunofluorescent labeling with quantum dots of the diabetes-associated proteins aldose reductase and Toll-like receptor 4 in the kidneys of diabetic rats

“…The approach of QD conjugated with Ab is various and complex 40,41 and there are various ways of identifying the conjugates, including mass spectrometry, capillary electrophoresis, and so on. 42 In this study, we set up QD-primary Ab probes with simple steps, omitting ultrafiltration and purification. In addition, the conjugating efficiency of the probes could be detected by agarose gel electrophoresis, providing a more convenient and effective way of using QD immunofluorescence in cellular imaging and tissue staining.…”

Capillary electrophoresis of quantum dots: Minireview

“…The simple adsorption of antibodies on the QDs surface as well as commonly used bioconjugation via organic linkers such as 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) or two‐step procedure combining EDC with N ‐hydroxysulfosuccinimide may lead to the inactivation of the antibody due to the sterically inappropriate binding. This was addressed in the work of Janu et al , where an artificial peptide was used as a linker with specificity to the Fc fragment of the antibody and therefore active site remained active (Fig. B).…”