The ability to design and arrange peptides with a controllable structure and chemical diversity would provide a class of self-assembled materials with sophisticated functions. We present the assembly of a designed tyrosine-rich peptide at the air/water interface, displaying facet formation of a water droplet. The identified peptides had a strong driving force to flatten the rounded top of droplet into a plane with a macroscopic 2D structure. The facet formation is driven by interactions of tyrosine and cross-linked stabilization by cysteine. We revealed the crucial sequence motifs for facet formation and their helical folding structures. The well-ordered redox active tyrosine in the 2D peptide film also can enhance chemical/electrochemical reaction.
In an effort to investigate the potential of tyrosine-rich peptide with redox active functions, we examine proton conductivity of the peptide films hybridized with manganese oxides. Proton conduction is an essential process to regulate the integral part of enzymatic catalysis and bioenergetics. To understand and manipulate proton conduction in bio-system, several studies have investigated bulk proton conduction of biomaterials. However, little is known about the bulk proton conductivity of short peptides and their sequence-dependent behaviour. We focus on tyrosine-rich peptide which has redox-active and crosslinkable phenol. The peptide/MnOx hybrid films can efficiently transport proton and proton conductivity was 18.6 mS cm-1. The value is much higher than that of biomaterials and comparable with synthetic materials. These results suggest that peptide-based hybrid material can be a promising new class of proton conductor.