Proton Conduction in a Tyrosine-Rich Peptide/Manganese Oxide Hybrid Nanofilm

5 years ago

Proton Conduction in a Tyrosine-Rich Peptide/Manganese Oxide Hybrid Nanofilm

Taehoon Sung, Ki Tae Nam, Young-O Kim, Ik Rang Choe, Jang-Yeon Kwon, Yoon-Sik Lee, Kyoungsuk Jin, Seok Daniel Namgung, Jaehun Lee, Hyo-Yong Ahn

Proton conduction is an essential process that regulates an integral part of several enzymatic catalyses and bioenergetics. Proton flows in biological entities are sensitively controlled by several mechanisms. To understand and manipulate proton conduction in biosystems, several studies have investigated bulk proton conduction in biomaterials such as polyaspartic acid, collagen, reflectin, serum albumin mats, and eumelanin. However, little is known about the bulk proton conductivity of short peptides and their sequence-dependent behavior. Here, this paper focuses on a short tyrosine-rich peptide that has redox-active and cross-linkable phenol groups. The spin-coated peptide nanofilm is immersed in potassium permanganate solution to induce cross-linking and oxidation, simultaneously leading to hybridization with manganese oxide (MnOx). The peptide/MnOx hybrid nanofilm can efficiently transport protons, and its proton conductivity is ≈18.6 mS cm−1 at room temperature. This value is much higher than that of biomaterials and comparable to those of other synthetic proton-conducting materials. These results suggest that peptide-based hybrid materials can be a promising new class of proton conductor. A new class of hybrid proton conductor composed of tyrosine-rich peptide and manganese oxide is synthesized. Electrical measurements and isotope analysis reveal that the main charge carrier of the hybrid film is a proton from water vapor. Interestingly, cross-linking and oxidation of tyrosine simultaneously lead to hybridization with MnOx, resulting in strong synergetic effects on proton conduction.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adfm.201702185