Hierarchically structured peptide nanofibers for colorimetric detection of gaseous aldehydes

We demonstrate a systematic approach to produce colored films based on hierarchical structures of peptide amphiphiles and their application for detecting gaseous aldehydes. Lysine-rich peptide amphiphiles (LRPAs) were designed to spontaneously self-assemble into nanofibers, which were deposited to form the colored films on solid substrates via controlled evaporation of the meniscus using a facile dipping-pulling method. The control of assembly conditions such as pH, concentration, and pulling speed enable the manifestation of film colors in a controllable way. When exposed to aldehyde gases, the color band pattern exhibited large color change due to structural change of the matrices which occur upon specific binding of aldehydes to lysine motifs. The statistical analysis of the color-change showed that the LRPA-based band patterns exhibit excellent selectivity toward aldehydes over non-aldehyde gases. We expect that our method will expedite the development of inexpensive, rapid and user-friendly aldehyde detection systems with on-site monitoring capabilities.