Chemoenzymatic synthesis of amylose-grafted poly(vinyl alcohol)

In this study, we synthesized an amylose-grafted poly(vinyl alcohol) (PVA) (4) by a chemoenzymatic method. First, synthesis of an amine-functionalized PVA (2) was carried out by reduction of an azide-functionalized PVA (1) using NaBH4. Then, introduction of maltoheptaose to 2 was performed by reductive amination using NaBH3CN to produce a maltoheptaose-grafted PVA (3). Finally, a phosphorylase-catalyzed enzymatic polymerization of α-D-glucose 1-phosphate from the maltoheptaose-chains in 3 was carried out to obtain 4. A film of 4 was prepared by drying its aqueous solution spread on a flat quartz glass substrate. An iodine-doped film was prepared by soaking the film of 4 in KI/I2ethanol solution. UV-Vis analysis indicated that iodine was retained in this film even after it was left standing for 24 h. This is probably because the iodide ion was within the cavities of the amylose graft chains in this film.