Synthesis and labeling of α-(2,9)-trisialic acid with cyanine dyes for imaging of glycan-binding receptors on living cells

Abstract

A sugar epitope, α-(2,9)-trisialic acid, was synthesized and labeled by cyanine dyes through Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The cyanine tagged oligosialic acid can be utilized as an efficient fluorescent probe to image the glycan-binding receptors on PC-12 cells. The distribution of Sia-binding immunoglobulin-like lectins (Siglecs) for α-(2,9)-trisialic acid was visualized by Cy3/Cy5 or FRET channel fluorescence imaging.

Cyanine Conjugate‐Based Biomedical Imaging Probes

“…For instance, based on endogenous α ‐(2,9)‐oligosialic acid sugar epitope and mannose, α ‐(2,9)‐trisialic acid and 2‐amino‐2‐deoxymannose were conjugated with cyanine fluorophores for targeted imaging of sia‐binding immunoglobulin‐like lectins on PC‐12 cells ( 16 ) and mannose receptors on tumor‐associated macrophages ( 17 ), respectively. [ 29 ] And it is more common in the case of endogeneous peptide ligands, wherein the so‐called peptidomimetic strategy is adopted to design warheads that mimic the receptor–ligand interaction. Some may still maintain the peptide‐like scaffolds, like octreotide, a cyclic octapeptide derived from native somatostatin with better metabolic stability due to the downsized ring and incorporation of d ‐amino acids.…”

Probing Sialidases or Siglecs with Sialic Acid Analogues, Clusters and Precursors

“…In 2015, our group studied the distribution of Siglecs on the surface of living cells with fluorescently‐labeled ligands . We first synthesized two α‐(2,9)‐trisialic acids (triSia‐Cy3 and triSia‐Cy5) labeled with cyanine dyes using Cu(I) catalyzed click reaction (Scheme ).…”

Design of multivalent fluorescent dendritic probes for site‐specific labeling of biomolecules

“…Moreover, scanners in microarray systems have the capacity for signal detection of Cy5. Most examples in literature detail the monovalent conjugation of Cy5 probes using simple bifunctional linkers . Dendrimers functionalized with Cy5 substituents, either at periphery or at focal point, have also been reported on as monodisperse scaffolds, including popular PAMAM or 2,2‐bis(methylol)propionic acid (bis‐MPA) architecture among others.…”

“…Dendrimers functionalized with Cy5 substituents, either at periphery or at focal point, have also been reported on as monodisperse scaffolds, including popular PAMAM or 2,2‐bis(methylol)propionic acid (bis‐MPA) architecture among others. The bioconjugation of Cy5 via covalent linkages to the target molecule often involves click chemistries although 1,2‐addition reaction, or reaction with amines through N ‐hydroxysuccinimide (NHS) chemistry have also been described. Of note is the use of hydrazide or hydrazine monovalent Cy5 probes, since they react selectively with carbohydrate on the Fc region of antibodies, with a well‐defined stoichiometry of conjugation, without affecting the binding site of the biomolecule.…”