Assembly of electroactive layer-by-layer films of myoglobin and small-molecular phytic acid

In the present work, small-molecular phytic acid (PA) with its unique structure was successfully assembled with myoglobin (Mb) into {PA/Mb}n layer-by-layer films on solid surfaces. Quartz crystal microbalance (QCM) and cyclic voltammetry (CV) were used to monitor or confirm the assembly process. IR and UV–vis spectroscopy indicate that the Mb in {PA/Mb}n films retains its near native structure. The direct electrochemistry of Mb was realized in this new kind of films at pyrolytic graphite (PG) electrodes, and was used to electrocatalyze the reduction of various substrates. The interaction between PA and Mb under different pH conditions was also explored. Not only the oppositely charged PA and Mb at pH 5.0, but also the likely charged PA and Mb at pH 9.0, could be assembled into {PA/Mb}n films. This work provides a novel avenue to fabricate protein multilayer films with small molecules and realizes the direct electrochemistry of redox proteins in the films.