Probing Lectin and Sperm with Carbohydrate‐Modified Quantum Dots

Abstract

We report the encapsulation of quantum dots with biologically important beta-N-acetylglucosamine (GlcNAc) in different ratios, together with studies of their specific/sensitive multivalent interactions with lectins and sperm by fluorimetry, transmission electron microscopy, dynamic light scattering microscopy, confocal imaging techniques, and flow cytometry. These GlcNAc-encapsulated quantum dots (QDGLNs) specifically bind to wheat germ agglutinin, and cause fluorescence quenching and aggregation. Further studies of QDGLNs and the mannose-encapsulated QDs (QDMANs) with sperm revealed site-specific interactions, in which QDGLNs bind to the head of the sperm, while QDMANs spread over the whole sperm body.

Fluorescently labelled glycans and their applications

“…QDs can also be readily modified on the surface to allow for the immobilization of multiple ligands, which is typically required in studying glycan-protein interactions. In this respect, N-acetylglucosamine bearing a sulfhydryl group at the reducing end through an alkyl linkage is readily attached to 5 nm CdSe/ZnS core-shell QDs [123]. It was determined that approximately 210 GlcNAc molecules were incorporated into each QD, and the fluorescence of the QDs is quenched in the presence of WGA lectin in a concentration-dependent fashion.…”

Multivalenz als chemisches Organisations‐ und Wirkprinzip

“…[66] Mit Methoden der Mikroskopie und mit dynamischer Lichtstreuung kann kolloidale Stabilität von nanopartikulären Systemen in Abhängigkeit von deren multivalenter Stabilisierung bestimmt werden, ebenso ist eine Messung von durch multivalente Wechselwirkungen induzierter Aggregation mçglich. [60,67] [61] Dissoziationskonstante Bindung multivalenter Proteinliganden an Lipiddoppelschichten [62] Dissoziationskonstante Bindung von Choleratoxinen an Phospholipidmembranen [83] Oberflächenplasmonenresonanz(SPR)-Spektroskopie ¾nderung im Refraktionsindex bei Ligand/Rezeptor Wechselwirkung (massenabhängig)…”

Solid-phase chemical tools for glycobiology

“…120 Pyridine-capped CdSe/ZnS coreshells were prepared and ligand exchange was effected by addition of the disulfide of 11-mercapto-undecylb-N-acetylglucosaminoside under reducing (sodium borohydride) conditions. Binding of the GNPs to WGA was monitored by partial (up to 50%) fluorescence quenching of the quantum dot upon addition of WGA, an effect ascribed to electron transfer from the quantum dot to amino acid residues on WGA.…”

“…120 High-quality TOPO (trioctylphosphine oxide) capped CdSe/ZnS core-shells were prepared by a one-pot procedure, and ligand exchange was effected by pyridine capping followed by addition of the disulfide of 11-mercapto-undecyl-b-N-acetylglucosaminoside under reducing (NaBH 4 ) conditions. The intermediate pyridine capping was used to attain a more efficient ligand displacement by the thiol-functionalized saccharide.…”