Study On The Preparation Of Phenylboronic Acid Derivatives And Its Recognition Of Saccharides

Saccharides are the main source of energy for our bodies and are involved in a surprising number of biological processes.Designing and synthesizing saccharides receptors with high sensitivity and practicability is an urgent need for biological,material and chemical scientists.Many saccharides have no structural differences other than the configuration of some stereocentric centers,which makes saccharides recognition a grand challenge.Saccharides recognition receptors which based on boronic acid have become the focus of researchers in recent years due to their reversible binding ability with 1,2-or 1,3-cis-diols via covalent bonds.The binding between boronic acid and saccharide depends on the orientation and relative position of the hydroxyl group,so that can distinguish sugar molecules with similar structures,thus boronic acid-based saccharides sensors have the potential for biological applications.Through the design of boric acid molecule,one part of organic boric acid molecule is hydrophilic boric acid group and the other end is hydrophobic organic skeleton,thus becoming a potential functional surfactant.It is a key concept in boronic acid design to selectively recognize saccharides by stimulating the morphological changes of the boronic acid self-assembly system.Based on this,a tuning-fork-shaped diboronic acid 6b was designed and synthesized,which can form vesicle aggregates by self-assembly in aqueous solution.The aggregate morphology of 6b and its complex with monosaccharides molecules was determined by transmission electron microscopy and dynamic light scattering.A larger aggregate was formed in 6b solution with addition of glucose,and the aggregate was broken and dispersed in 6b solution in the presence of fructose.The interaction of 6b with three monosaccharides was studied by UV titration.The complex of 6b with fructose and galactose was 1:1,and the stoichiometric ratio of 6b to glucose was 1:2.Self-assembly increases the density of boronic acid groups on the surface of aggregates,but the result of this self-assembly is a 1:2 complex with glucose,rather than the cross-linking of diboronic acid molecules with glucose.Therefore,several possible combinations of glucose and 6b were optimized by theoretical simulation and single point energy calculation to explain the binding mode of glucose and 6b.Fluorescence detection technology is an indispensable tool in the field of modern chemical detection.In this paper,borate carbohydrate receptor 10a-c with pyridine cation salt was designed and synthesized,and a two-component fluorescence detection system was formed with anionic dye 8-hydroxypyrene-1,3,6-trisulfonate(HPTS).In the presence of pyridine cation salt 10a-c,the fluorescence of HPTS is quenched due to electrostatic interaction.Adding saccharides,the formation of cyclic borate esters dissociates the ion pairs and recovers the fluorescence of HPTS.This system has a higher quenching efficiency compared with other systems reported previously.It can detect the concentration of glucose in physiological range by fluorescence method at physiological pH,and has strong sensitivity.Boronic acid modified polymers have attracted more and more attention in the field of reactive polymers and polymer materials.Therefore,based on a highly sensitive two-component fluorescence system for the detection of glucose concentration,a phenylboronic acid derivative 14a-b of pyridine cationic salt with double bonds was designed and synthesized.Acrylamide was selected as hydrogel matrix to investigate the fluorescence recovery of hydrogel films formed at different quencher/dye ratios in different concentration of glucose solution.The hydrogel film has good fluorescence recovery efficiency in the range of physiological glucose concentration.The hydrogel film system can be used as a monitoring equipment for blood sugar detection in diabetic patients.