A Photoinduced Reversible Phase Transition in a Dipeptide Supramolecular Assembly

Abstract

Tunable supramolecular assembly has found various applications in biomedicine,molecular catalysis,optoelectronics,a nd nanofabrication. Unlike traditional covalent conjugation, non-covalent introduction of ap hotoswitchable moiety enables reversible photomodulation of non-photosensitive dipeptide supramolecular assembly.U nder light illumination, along-lived photoacid generator releases aproton and mediates the dissociation of dipeptide-based organogel, therebyresulting in sol formation. Under darkness,the photoswitchable moiety entraps ap roton, resulting in gel regeneration. Furthermore,a ccompanying the isothermal recycled gel-sol transition in as patially controlled manner,r enewable patterns are spontaneously fabricated. This new concept of light-controlled phase transition of amino acid-based supramolecular assemblies will open up the possibility of wide applications.

High-Efficiency Fluorescence through Bioinspired Supramolecular Self-Assembly

“…Bioorganic molecules with intrinsic fluorescence are highly desired in biomedicine and biotechnology as they allow the tracking and monitoring of fundamental biological processes without complicated and potentially toxic labeling. − The search for alternatives that offer higher performance and ease of tunability, such as flexible, functional modulation and enhanced eco-friendliness, is still ongoing. − Peptides, as a natural ingredient of biological systems, self-assembling through extensive and directed hydrogen bonding, and aromatic interactions, are intriguing candidates for this purpose, thus prompting extensive efforts to utilize these properties toward developing next-generation functional biomaterials. − The most prominent example is diphenylalanine, a dipeptide initially identified as the smallest core recognition motif of β-amyloid, the amyloidogenic polypeptide associated with Alzheimer’s disease, which self-assembles into diverse nanostructures potentially useful in the biomedical field for biosensing. − However, the majority of intrinsically fluorescent peptides have low quantum yields and photostability, which severely hinders their practical applications and specifically limits their potential as eco-friendly materials for optoelectronic devices and efficient bioimaging probes …”

Reversible disassembly of metallasupramolecular structures mediated by a metastable-state photoacid

“… 12 Since then, PAH and structurally related compounds have been used in the context of supramolecular chemistry. Applications include the light-induced complexation of a pyridinium salt by a macrocyclic receptor, 13 the switching of a rotaxane-based molecular shuttle, 14 the light-controlled reversible self-assembly of nanorods, 15 the reversible chromism of guests in coordination cages, 16 the modulation of a hydrazine switch, 17 the reversible photo-induced gel–sol transition of a dipeptide gel, 18 and the controlled aggregation of nanoparticles, 19 among others. 11 , 20 We wanted to explore if PAH is also suited for controlling the structures of metal–ligand assemblies by light.…”

Fluorescence Spectroscopy of Porphyrins and Phthalocyanines: Some Insights into Supramolecular Self-Assembly, Microencapsulation, and Imaging Microscopy

“…The tracking and monitoring of fundamental biological processes without complicated and potentially toxic labeling can be made with bioorganic molecules with intrinsic fluorescence [52][53][54][55][56][57]. As a natural ingredient of biological systems, peptides are strong candidates for self-assembly through extensive and directed hydrogen bonding, and aromatic interactions, thus prompting extensive efforts to channel these features into the development of the next-generation of functional biomaterials [58][59][60][61][62][63][64][65][66][67][68][69][70]. One noticeable example is diphenylalanine that self-assembles into diverse nanostructures potentially useful in the biomedical field for biosensing.…”