Distinct Electrostatic Interactions Govern the Chiro-Optical Properties and Architectural Arrangement of Peptide–Oligothiophene Hybrid Materials

Abstract

The development of chiral optoelectronic materials are of great interest due to their potential of being utilized in electronic devices, biosensors and artificial enzymes. Herein, we report the chiral-optical properties and architectural arrangement of optoelectronic materials generated from non-covalent self-assembly of a cationic synthetic peptide and five chemically defined anionic pentameric oligothiophenes. The peptide-oligothiophene hybrid materials exhibit a three dimensional ordered helical structure and optical activity in the π-π* transition region that are observed due to a single chain induced chirality of the conjugated thiophene backbone upon interaction with the peptide. The latter property is highly dependent on electrostatic interactions between the peptide and the oligothiophene, verifying that a distinct spacing of the carboxyl groups along the thiophene backbone is a major chemical determinant for having a hybrid material with distinct optoelectronic properties. The necessity of the electrostatic interaction between specific carboxyl functionalities along the thiophene backbone and the lysine residues of the peptide, as well as the induced circular dichroism of the thiophene backbone, was also confirmed by theoretical calculations. We foresee that our findings will aid in designing optoelectronic materials with dynamic architectonical precisions, as well as offer the possibility to create the next generation of materials for organic electronics and organic bioelectronics.

Optotracing for selective fluorescence-based detection, visualization and quantification of live S. aureus in real-time

“…To contrast this, optotracing was developed as a nontoxic alternative for detection of polymeric substances. Optotracers are small, chemically well-defined, anionic fluorescent tracer molecules based on luminescent conjugated oligothiophenes, which via electrostatic interactions bind their target molecules 7,8 . Binding to specific biological targets can be controlled by chemical design, enabling tailored charge distribution along the conjugated thiophene backbone.…”

Multimodal Porphyrin-Based Conjugates: Synthesis and characterization for applications as amyloid ligands, photodynamic therapy agents and chiroptical materials

“…Nevertheless, a higher ratio of the two minima (q222/q208) for the OTPH3-JR2K complex is indicative of a slightly different helical structure than for OTPH1-JR2K. JR2K peptide does gain an a-helical structure even from interactions with porphyrin P3 and to a lesser extent with P1, as well as with pFTAA as already established in earlier published literature 130 . Furthermore, intense bisignate induced CD (ICD) signals are observed for the guest molecules at the expected wavelengths for their absorption, which proves their incorporation into higher-order complexes with the peptide.…”

“…The structural arrangements were accompanied with induced chiroptical activity. 130 OTPHs, featuring pFTAA and an additional molecular moiety with appealing structural and photophysical qualities in form of porphyrins, make attractive guest molecules for hybrid bioorganic materials. As described earlier, biomoleculebased materials offer great advantages of soft and static structure resulting from conformational flexibility of the biomolecular components.…”

“…The most evident shift was observed for pFTAA-JR2K, which is in accordance with a previously published study. 130 The redshifts in absorption and emission maxima may indicate that upon interaction with JR2K these probes adopt a more planar conformation resulting in a longer effective conjugation. In addition, increased emission was detected for OTPH1 and OTPH3 while interacting with JR2K.…”

Peptide-Liposome Model Systems for Triggered Release

“…An α-helix is the structure adopted when the peptide backbone forms a spiral structure, The absence of a defined secondary structure is referred to as random coil. [19] Changes in secondary structures can occur due to changes in various physicochemical factors such as temperature, [78] pH, [79] , ionic strength, [80] metal ion coordination [81] and through specific or unspecific interactions with other small molecules [82] or peptides. [83][84][85] The interaction of peptides with interfaces, such as nanoparticle surfaces [86] and lipid bilayers, [87] can also induce changes in secondary structure.…”