Modulation of Semiconducting Behavior and a Change in Morphology upon Gelation of a Peptide Appended Naphthalenediimide

Abstract

A dipeptide-appended naphthalenediimide (NDI) is self-assembled in an aqueous phosphate buffer medium of pH 7.5 to form nanovesicular structures. Interestingly, these molecules are assembled to form hydrogels in the presence of glucono-δ-lactone (at pH 4.7) or Ru3+ solution (at pH 4.6). The gel formation is associated with a sharp morphological change from nanospheres to a nanofibrous network structure, and this nanofibrous network is responsible to trapping of many solvent molecules to form hydrogels. These gels and aggregates are well characterized by different spectroscopic and microscopic tools including UV–vis absorption and fluorescence spectroscopy, Fourier transformed infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD), rheological studies, and high resolution transmission electron microscopic (HR-TEM) studies. The peptide-appended NDI was found to form J-aggregate as is evident from the UV–vis absorption studies of the aggregated species. Upon excitation at 384 nm wavelength, the glucono-δ-lactone-based hydrogel shows a greenish blue fluorescence, and similar fluorescence is observed for the aggregates of NDI-appended peptide in aqueous buffer medium at pH 7.5. The soluble aggregates and both gels (obtained from the treatment of glucono-δ-lactone and Ru3+) show wonderful current conduction and photoswitching properties. The photoconductivity and the gain in photocurrent values are enhanced in the GDL and Ru3+ mediated gels by several orders. This indicates that the morphological change from nanovesicles to ordered network of fibers has an important role in the enhancement of photocurrent gain in photoswitching experiments.

Peptide-Based Gel in Environmental Remediation: Removal of Toxic Organic Dyes and Hazardous Pb2+ and Cd2+ Ions from Wastewater and Oil Spill Recovery

“…Supramolecular gels − consisting of a variety of small organic molecules have attracted researchers’ attention in the last few decades because of their various applications in chemical, material, and biological sciences. − Among low-molecular weight gelators, peptide amphiphiles belong to a special category because they provide a distinctive opportunity to design soft materials with controllable structural features and specific secondary structures. The predictable structure–function relationships of the naturally occurring amino acids can thus be utilized to obtain materials with desirable properties .…”

Development of Polythiophene–Tripeptide Covalent Conjugates Showing Excellent Structure-Dependent Photophysical and Photocurrent Properties

“…The conjugation of biological entities like peptides into a conducting polymeric matrix both covalently and non-covalently offers potential to build diverse bio-electronic materials, making them useful for biotechnology. , Short peptide- or oligopeptide-based soft materials have become very conspicuous in this respect due to their inherent biocompatibility, structural diversity, tunable bioactivity, and also their easy and low-cost synthesis. These offer vast potential in biotechnological, biomedical, biochemical, oil spill recovery, and non-biological applications. − The dihedral angles between the adjacent peptide planes governed by hydrogen-bonding interaction generate α-helices, β-sheets, β-turns, fibers, micelles, vesicles, ribbons, tubes, tapes, and coil-like morphologies . The formation of these types of 3D network structural motifs is dependent on the specific amino acid sequence …”

Investigation of the Mechanism Behind Conductive Fluorescent and Multistimuli‐responsive Li+‐enriched Metallogel Formation

“…Coordination of alkali/ transition/lanthanide metal ions to appropriately designed ligands produces metallogels which may demonstrate the unique optical/fluorescent as well as other metal associated properties . Due to appearance of unique fluorescence property in metallogels, these materials could be utilized for sensing, cell imaging, security writing, etc .…”