Preparation of multilayer films using the negative charge of phenylboronic acid and its response to pH change, fructose, and hydrogen peroxide

Functional layer-by-layer (LbL) multilayer films using phenylboronic acid (PBA) have been typically prepared by exploiting the boronate ester bond between PBA and a diol polymer as the driving force. However, we have prepared PBA-containing LbL films through the electrostatic interaction of PBA and polycations, Poly(acrylamide-ran-3-acrylamidephenylboronic acid) (PBA-PAA) and various polycations such as poly(allylamine) hydrochloride (PAH), poly(ethyleneimine) (PEI), poly(diallyldimethylammonium chloride) (PDDA), and polyamidoamine (PAMAM) dendrimer were used. Construction of the multilayer films was influenced by the modification ratio of PBA, the shape of the polycations, solution pH, and the ion concentration. The results showed that the multilayered film was formed by electrostatic interaction. A multilayer film prepared from 10% PBA containing PBA-PAA and PAH showed pH, fructose, and H₂O₂ responses because these stimuli disturbed the charge balance inside the multilayer films. Such decomposition responses were comparable to that of PBA multilayer films constructed using boronate ester bonds.