β-Boronic Acid-Substituted Bodipy Dyes for Fluorescence Anisotropy Analysis of Carbohydrate Binding

Abstract

Boronic acids are widely used for labeling catechols and carbohydrates in analytical (bio)­chemistry due to their high binding affinities for diols. Here, we present two asymmetrically substituted Bodipy dyes with a boronic acid at the β-position (BBB). We present a green-emitting BBB, gBBB, and, by expanding the conjugated system of the Bodipy core at α-position, a red-emitting rBBB. Especially, gBBB shows a bathochromic shift of the electronic spectra upon binding to saccharides and polyols, whereas the fluorescence lifetime of rBBB is more sensitive to hydroxy-ligand binding. Moreover, gBBB constantly shows higher binding affinities than rBBB, reaching K b ≈ 103 M–1 at pH 8.5 for fructose. Finally, time-resolved fluorescence anisotropy allows to distinguish the number of saccharide units of oligosaccharides as the bond along the transition dipole moment ensures that the fluorescence anisotropy only decays due to the rotational diffusion of labeled carbohydrates. β-substituted BODIPY dyes are, thus, foreseen as fluorescence anisotropy labels for macromolecule sizing, where conventional fluorophores fail to discriminate due to the chemical similarity of recognition sites.

Characterization of the 1-(5-(4,5-Dimethyl-1,3,2-dioxoborolan-2-yl)thiophen-2-yl)ethanone Using NMR 13C, 1H and 11B through the Density Functional Theory

“…The compounds with boronate esters represent valuable means in organic synthesis, particularly in the Suzuki-Miyaura coupling reaction [12]. They are useful for carbohydrate detection [13] due to their capacity to produce cyclic esters with suitable diols [14]. They show biological activities, such as antidepressant, antiallergic, anesthetic, and anti-Alzheimer agents, as well as proteasome and lipogenic inhibitors [15].…”

Sensitive and specific detection of saccharide species based on fluorescence: update from 2016

“…Because of the high binding affinity of phenylboronic acid for cis -diols, various fluorophores with appended boronic acids have been designed for direct carbohydrate binding [ 36 ]. In this regard, molecules with vibration-induced luminescence (VIE) [ 37 ] and aggregation-induced luminescence (AIE) [ 38 ] properties were explored for glucose detection.…”

De Novo Access to BODIPY C-Glycosides as Linker-Free Nonsymmetrical BODIPY-Carbohydrate Conjugates

“…For example, the carbohydrate moiety has been shown to internalize, solubilize in water, target, and reduce the cytotoxicity of the fluorophore . Conversely, the presence of the fluorophore in BODIPY-carbohydrate conjugates has shown its value in the investigation of carbohydrate-receptor interactions in biological systems with high sensitivity, by way of fluorescently labeled carbohydrates. ,, …”