Controlled Functionalization of Water-Soluble Semiconductor Quantum Dots for Bioconjugation

• Published in: Journal of applied spectroscopy Vol. 86; no. 6; pp. 1064 - 1070
• Main Authors: Ranishenka, B. A., Ulashchik, E. A., Kruhlik, A. S., Tatulchenkov, M. Yu, Radchanka, A. V., Shmanai, V. V., Artemyev, M. V.
• Format: Journal Article
• Language: English
• Published: New York Springer US 2020; Springer; Springer Nature B.V
• Subjects: Albumin; Alkynes; Amines; Analytical Chemistry; Atomic/Molecular Structure and Spectra; Azide; Azides (organic); Cadmium selenides; Conjugation; Cycloaddition; Density; Dyes; Electrons; Ethanolamines; Fluorescence; Functional groups; Phosphines; Physics; Physics and Astronomy; Quantum dots; Reaction kinetics; Reducing agents; Serum albumin; Sulfates; Surface active agents; click-chemistry; azide groups; bioconjugation; tris(2-carboxyethyl)phosphine; semiconductor quantum dots; ζ-potential; carbodiimide condensation
• ISSN: 0021-9037; 1573-8647
• DOI: 10.1007/s10812-020-00941-3

A one-step procedure using carbodiimide condensation was proposed for controlled functionalization of watersoluble semiconductor quantum dots (QDs) with azide groups. The changes of functional group surface density and ζ-potential could be controlled during modifi cation of anionic and analogous zwitterionic polymer-encapsulated CdSe/ZnS core–shell QDs. Ethanolamine-O-sulfate, aminotetraethylene glycol (H 2 N–TEG–OH), and aminotetraethylene glycol azide (H 2 N–TEG–N 3 ) were used as modifiers. Functionalization was investigated by studying the conjugation kinetics of organic dye JOE to QDs using strain-promoted azide-alkyne cycloaddition (SPAAC). The reactivity of QDs in SPAAC was nearly proportional to the relative density of surface azides. The QD ζ-potential correlated with the ratio of modifiers. Azides on the QD surface could be easily transformed under mild conditions into primary amines using tris(2-carboxyethyl)phosphine as a reducing agent. The applicability of surface-functionalized QDs for bioconjugation was demonstrated via conjugation to fluorescent-dye-labeled bovine serum albumin.