Printable Fluorescent Hydrogels Based on Self-Assembling Peptides

Yifan Xia,Bin Xue,Yi Cao,Wei Wang,Ying Li,Meng Qin

doi:10.1038/s41598-017-10162-y

Abstract

Fluorescent hydrogels (FH) have a variety of potential applications in the field of soft electronics. However, fabrication of mechanically stable and printable fluorescent hydrogels remains challenging. Here, we report a kind of fluorescent hydrogel based on the co-assembly of peptide motif and transition metal ions. The metal ions are captured in the hydrogel network at specific positions through covalently linked ligands on the peptide hydrogelators. This efficiently prevents the aggregation and self-quenching of organometallic chromophores. In addition, the formation of metal-ligand complexes introduces additional interactions to stabilize the hydrogel network, making the FH even more stable after the incorporation of metal ions. The FH is optically transparent but highly fluorescent. By using three different metal ions, the white light fluorescent supramolecular hydrogel has been achieved. As a proof-of-principle, we demonstrate the printability of the hydrogels to various patterns. We anticipate that with the improved fluorescent performance and stability, this kind of FH can find broad applications in extrusion-based 3D printing for the construction of soft electronics.

Highlights

Because the metal ions are fixed to the hydrogel network at specific positions, the aggregation and self-quenching of chromophores are prevented
Many short peptides are well known for their ability to self-assemble into fibrous network structures and form supramolecular hydrogels
The N-terminus of the peptide was capped with the powerful ligand, 2,2′-bipyridine, for metal ion chelation

Summary

Introduction

Among the light-emitting materials, white-luminescent solid materials based on supramolecular design have been extensively investigated because the organization of donors and acceptors can be modulated by rationally designing the self-assembled supramolecular structures of the nanomaterials, such as hydrogel[23, 27,28,29,30], nanofibres[31,32,33,34], nanoparticles[28, 35,36,37], and etc[38,39,40]. By rational design, it is possible to further improve the fluorescent properties of FH by rigidifying the donor−acceptor pairs and reducing the nonradiative decay Another advantage of FH, especially the supramolecular ones, is their unique physical properties: They are often elastic, injectable and healable after damage. Lack of direct chemical bonding of the dye molecules with the hydrogel network may cause the leaking of the fluorescent materials as well as the aggregation of the chromophores, leading to fluorescence quenching and reduction of luminescence[55, 56]. The structural, physical and optical properties of the hydrogels were studied in details This type of FH based on self-assembled peptides shows high transmittance, color-switchable luminescence and great stability in water. We anticipate that with the improved fluorescent performance and stability, this kind of FH can find broad applications in 3D printable soft electronics

Methods

Results

Discussion

Conclusion