Synthesis of boronic acid-immobilized monodispersed porous polymer resins using a templating polymerization technique, and their application to packings for separation of saccharides

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Boronic acids form stable cyclic esters with cis-diols of saccharides, and therefore are used in the separation of nucleosides, nucleotides, and glycated proteins such as a glycated hemoglobin. In these investigations boronic acids covalently bound to carriers such as silica gel. and polymer resins were used for the separation. However, pH range of silica gel packed column has been limited by the unstability in alkaline solution. On the other hand, the nonuniformity in particle size of the polymer resins is unavoidable in the conventional preparation method, and lowers the resolution efficiency of a chromatographic column.For separation of saccharides and glycoconjugates, we prepared two types of monodispersed boronic acid immobilized porous styrene-divinylbenzene copolymer particles using a polymerization method based on a templating technique. The polymer particles with 5 μ m particle size was used as the stationary phase for high-performance liquid chromatography. The results of HPLC separation of aldohexoses and aldopentoses revealed that ribose, talose and idose were retained in boronic acid immobilized polymer resins in the pH range of 1.3 〜 11.9. These saccharides exist considerably as a furanose form in an aqueous solution, and therefore, a furanose form probably plays important role in the complex formation between a boronoic acid and saccharides. On the other hand, the solid phase extraction by the polymer particles with 20 μ m particle size was applied to glucose, talose and ganglioside G^<M1>. However no retention with these compounds was observed. This result shows that higher extent of immobilization with boronic acid groups on the polymer surface was required for the solid phase extraction.