Seamless Metallic Coating and Surface Adhesion of Self-Assembled Bioinspired Nanostructures Based on Di-(3,4-dihydroxy‑l‑phenylalanine) Peptide Motif

• Published in: ACS nano Vol. 8; no. 7; pp. 7220 - 7228
• Main Authors: Fichman, Galit, Adler-Abramovich, Lihi, Manohar, Suresh, Mironi-Harpaz, Iris, Guterman, Tom, Seliktar, Dror, Messersmith, Phillip B, Gazit, Ehud
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-07-2014
• Subjects: Adhesiveness; Amino Acid Motifs; Biomimetic Materials - chemistry; Dihydroxyphenylalanine - chemistry; Dipeptides - chemistry; Drug Design; Fluorenes - chemistry; Hydrogels - chemistry; Metal Nanoparticles - chemistry; Nanostructures - chemistry; Silver - chemistry; Surface Properties; supramolecular polymers; metallic coating; self-assembly; peptide nanostructures; bioinspired materials
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn502240r

The noncoded aromatic 3,4-dihydroxy-l-phenyl­alanine (DOPA) amino acid has a pivotal role in the remarkable adhesive properties displayed by marine mussels. These properties have inspired the design of adhesive chemical entities through various synthetic approaches. DOPA-containing bioinspired polymers have a broad functional appeal beyond adhesion due to the diverse chemical interactions presented by the catechol moieties. Here, we harnessed the molecular self-assembly abilities of very short peptide motifs to develop analogous DOPA-containing supra­molecular polymers. The DOPA-containing DOPA–DOPA and Fmoc–DOPA–DOPA building blocks were designed by substituting the phenyl­alanines in the well-studied diphenyl­alanine self-assembling motif and its 9-fluorenyl­methoxy­carbonyl (Fmoc)-protected derivative. These peptides self-organized into fibrillar nanoassemblies, displaying high density of catechol functional groups. Furthermore, the Fmoc–DOPA–DOPA peptide was found to act as a low molecular weight hydro­gelator, forming self-supporting hydrogel which was rheologically characterized. We studied these assemblies using electron microscopy and explored their applicative potential by examining their ability to spontaneously reduce metal cations into elementary metal. By applying ionic silver to the hydrogel, we observed efficient reduction into silver nanoparticles and the remarkable seamless metallic coating of the assemblies. Similar redox abilities were observed with the DOPA–DOPA assemblies. In an effort to impart adhesiveness to the obtained assemblies, we incorporated lysine (Lys) into the Fmoc–DOPA–DOPA building block. The assemblies of Fmoc–DOPA–DOPA–Lys were capable of gluing together glass surfaces, and their adhesion properties were investigated using atomic force microscopy. Taken together, a class of DOPA-containing self-assembling peptides was designed. These nano­assemblies display unique properties and can serve as multi­functional platforms for various bio­technological applications.