A sugar chain exists on the surface of cell membranes, and it is responsible for a biological reaction on the cell membrane surface. Therefore, it is considered that call characteristics can be controlled by obtaining a material specifically interacting with sugar chain. In this research, we aimed to develop polymeric materials having sugar chain affinity. Since boronic acid interacts with diols, they can be expected to act as recognition sites for sugar chains on cell membranes. However, since many boronic acid compounds recognize sugars under basic conditions and form boronic acid ester bonds, it is considered difficult to use them under neutral conditions. We focused on benzoxaborole (BOx), which has strong interaction with diol under physiological condition (pH 7.4). In order to obtain polymers with boronic acid species having sugar chain affinity at neutral condition, hydrophilic polymers containing BOx units were synthesized and their sugar binding properties in water were evaluated. PDBM-co-PBBM (PDBO) having BOx unit was obtained from RAFT polymerization of N, N-dimethylacrylamide (DMA) and 1,2-benzoxaborole-5-methacrylamide. As a comparison, phenyl boronic acid (PBA) containing polymer, PDBM-co-PMAPBA (PDPB) was also obtained by the copolymerization of methacrylamide-3-phenylaboronic acid and DMA. As a result of 1H NMR, the number average molar masses of PDBO and PDPB were determined as 17,000 and 16,500 g mol-1, respectively. For the evaluation of sugar binding ability, UV-vis absorption and fluorescence measurements were carried out using Alizarin Red S (ARS). Polymer solutions containing constant ratio of ARS were prepared. A certain amount of glucose, fructose, and sialic acid was added to the polymer solution, and the fluorescence spectrum was measured. Because ARS shows fluorescence at 575 nm by binding with boronic acid, the fluorescence intensity of ARS decreases when polymer interacts with sugar molecules. The sugar binding ability was determined from the rate of decrease in fluorescence intensities when sugar molecules were added. PDBO showed higher sugar binding ability than PDPB at pH 7.4. The difference of PDBO and PDPB in the affinity to fructose and glucose was small, however a significant increase in affinity to sialic acid was confirmed for PDBO. It was found that BOx-containing PDBO exhibited high binding ability to sialic acid under physiological conditions.

Synthesis and evaluation of benzoxaborole containing polymers having sugar chain affinity (III) - Effect of boronic acid species on sugar binding ability

256th National Meeting (2018)

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