Cyanine Dye Coupling Mediates Self‐assembly of a pH Sensitive Peptide into Novel 3D Architectures

Abstract

Synthetic multichromophore systems are of great importance in artificial light harvesting devices, organic optoelectronics, tumor imaging and therapy. Here, we introduce a promising strategy for the construction of selfassembled peptide templated dye stacks based on coupling of a de novo designed pH sensitive peptide with a cyanine dye Cy5 at its N-terminus. Microscopic techniques, in particular cryogenic TEM (cryo-TEM) and cryo-electron tomography technique (cryo-ET), reveal two types of highly ordered three-dimensional assembly structures on the micrometer scale. Unbranched compact layered rods are observed at pH 7.4 and two-dimensional membrane-like assemblies at pH 3.4, both species displaying spectral features of H-aggregates. Molecular dynamics simulations reveal that the coupling of Cy5 moieties promotes the formation of both ultrastructures, whereas the protonation states of acidic and basic amino acid side chains dictates their ultimate three-dimensional organization.

Self-Assembly and Disassembly of Membrane Curvature-Sensing Peptide-Based Deep-Red Fluorescent Probe for Highly Sensitive Sensing of Exosomes

“…The observation of the blue-shifted absorption (530 nm) compared to the parent dye indicates the H-aggregation of the TR units . The absorption band over 650 nm might result from the Davydov splitting due to the oblique geometric configuration of the TR units in the aggregates . It should be noted that the microscopic techniques such as AFM and cryogenic TEM (Cryo-TEM) are needed for further structural analysis of the formed aggregates.…”

Construction of Targeting-Peptide-Based Imaging Reagents and Their Application in Bioimaging

“…(b) Linear representation of STAP1 showing the N -terminal Cy5 dye indicated by a blue star. Reprinted with permission from ref . Copyright 2022 Wiley.…”

“…This residue arrangement guides the folding of amphipathic helices, which associate through their hydrophobic (a/d) faces (Figure a). The helices are intertwined, in which interhelical side chains pack in a characteristic “knob-in-hole” manner. , Following this strategy, Koksch et al de novo designed the pH-sensitive coiled-coil sequence and further coupled the cyanine dye Cy5 at its N-terminal end. This molecule demonstrated pH-responsive assembly behaviors and exhibited spectral features of H-aggregates, which could be further applied in tumor imaging (Figure b).…”

Electronic Structure and Excited-State Dynamics of DNA-Templated Monomers and Aggregates of Asymmetric Polymethine Dyes

“…Another way to form dye aggregates is to use large biomacromolecules, such as proteins, as a template. Proteins are useful in forming dye aggregates, as is evident in their use in photosynthetic light harvesting complexes. , While considerable advances have been made in predicting protein folding, − one drawback of this approach is that understanding how proteins fold in the presence of dyes is only in a nascent stage . Alternatively, deoxyribonucleic acid (DNA) has been proven to be a powerful template for the formation of dye aggregates.…”

“… 5 , 82 While considerable advances have been made in predicting protein folding, 83 − 87 one drawback of this approach is that understanding how proteins fold in the presence of dyes is only in a nascent stage. 88 Alternatively, deoxyribonucleic acid (DNA) has been proven to be a powerful template for the formation of dye aggregates. The simple basis of only four nucleotides that self-assemble via Watson–Crick base pairing allows for the precise formation of DNA nanostructures, including duplexes, four-armed Holliday junctions (HJs), and other high-order structures.…”