Abstract
Short peptides made from repeating units of phenylalanine self‐assemble into a remarkable variety of micro‐ and nanostructures including tubes, tapes, spheres, and fibrils. These bio‐organic structures are found to possess striking mechanical, electrical, and optical properties, which are rarely seen in organic materials, and are therefore shown useful for diverse applications including regenerative medicine, targeted drug delivery, and biocompatible fluorescent probes. Consequently, finding new optical properties in these materials can significantly advance their practical use, for example, by allowing new ways to visualize, manipulate, and utilize them in new, in vivo, sensing applications. Here, by leveraging a unique electro‐optic phase microscopy technique, combined with traditional structural analysis, it is measured in di‐ and triphenylalanine peptide structures a surprisingly large electro‐optic response of the same order as the best performing inorganic crystals. In addition, spontaneous domain formation is observed in triphenylalanine tapes, and the origin of their electro‐optic activity is unveiled to be related to a porous triclinic structure, with extensive antiparallel beta‐sheet arrangement. The strong electro‐optic response of these porous peptide structures with the capability of hosting guest molecules opens the door to create new biocompatible, environmental friendly functional materials for electro‐optic applications, including biomedical imaging, sensing, and optical manipulation.
Highlights
Short peptides made from repeating units of phenylalanine self-assemble into a remarkable variety of micro- and nanostructures including tubes, important biocompatible applications.[1,2,3,4,5] A privileged position among self-assembling peptides is reserved for short phetapes, spheres, and fibrils
Spontaneous domain formation is observed in triphenylalanine peptides or proteins, that were shown to tapes, and the origin of their electro-optic activity is unveiled to be related to a be involved in several degenerative disporous triclinic structure, with extensive antiparallel beta-sheet arrangement
We examined two types of polypeptide structures, from FF tubes and triphenylalanine (FFF)-tapes and FF-tubes (Figure 1)
Summary
We examined two types of polypeptide structures, FFF-tapes and FF-tubes (Figure 1). The FFF-tapes grow into elongated structures with rectangular cross sections. The scanning image of the Θ signal of PLEOM (Figure 3d) was relatively uniform across the tape, only changing at the left and right sides where the electrodes reside, and the signal becomes severely attenuated (observed in the retardance image) This constant Θ value across the entire FFF-tape measurement area suggests a single domain structure due to the sensitivity of the phase to the orientation of the molecular dipoles in the peptide crystal. Www.advancedsciencenews.com of FFF-tapes was carried out in a τ-interferometer equipped custom microscope (see the Experimental Section).[37] The resultant optical path difference of the orthogonal axes, together with the known thickness of the tape allows us to determine the refractive indices of the crystal. This result is similar to equivalent coefficients of commercially available inorganic electro-optic crystals such as Barium borate (BBO).[30]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
