Recognition of d‑Glucose in Water with Excellent Sensitivity, Selectivity, and Chiral Selectivity Using γ‑Cyclodextrin and Fluorescent Boronic Acid Inclusion Complexes Having a Pseudo-diboronic Acid Moiety

• Published in: ACS sensors 2023-01, Vol.8 (1), p.218-227
• Main Authors: Suzuki, Yota, Mizuta, Yuji, Mikagi, Ayame, Misawa-Suzuki, Tomoyo, Tsuchido, Yuji, Sugaya, Tomoaki, Hashimoto, Takeshi, Ema, Kazuhiro, Hayashita, Takashi
• Format: Article
• Language: English
• Subjects: Boronic Acids - chemistry; Coloring Agents; gamma-Cyclodextrins - chemistry; Glucose - chemistry; Water - chemistry
• ISSN: 2379-3694; 2379-3694
• DOI: 10.1021/acssensors.2c02087

Fluorescence recognition of d-glucose in water with excellent sensitivity, selectivity, and chiral selectivity is desired because d-glucose is an essential component in biological and pathological processes. We report an innovative approach that exploits the 1:2 stoichiometric inclusion complexes of γ-cyclodextrin (γ-CyD) with two molecules of fluorescent monoboronic acid-based receptors, which form a pseudo-diboronic acid moiety as the recognition site for d-glucose in water. Two monoboronic acids (1F and 2N) were easily synthesized without heating or column purification. The 1:2 stoichiometric inclusion complexes (1F/γ-CyD and 2N/γ-CyD) were prepared in a mixture of dimethyl sulfoxide/water (2/98 in v/v) by mixing γ-CyD and the corresponding monoboronic acids. Both 1F/γ-CyD and 2N/γ-CyD exhibited strong turn-on response to d-glucose with excellent selectivity over nine other saccharides in the water-rich solvent at pH 7.4 owing to the ditopic recognition of d-glucose by the pseudo-diboronic acid moieties. The limits of detection of 1F/γ-CyD and 2N/γ-CyD for d-glucose were 1.1 and 1.8 μM, respectively, indicating the remarkable sensitivity for the detection of d-glucose at μM levels. 1F/γ-CyD and 2N/γ-CyD also demonstrated chiral-selective recognition of d-glucose, which is apparent from the 2.0- and 6.3-fold enhancement of fluorescence by the addition of d-glucose relative to l-glucose addition, owing to the chiral pseudo-diboronic acid moieties produced by the chiral γ-CyD cavity. To the best of our knowledge, 2N/γ-CyD has the highest d/l selectivity among hitherto reported fluorescent diboronic acid-based receptors.