Nanostructure Formation through β-Sheet Self-Assembly in Silk-Based Materials

Abstract

Biomolecular Bombyx mori silk-based multiblock copolymers of poly(ethylene oxide)(PEO) and GlyAlaGlyAla prepared by step-growth polymerization based on a modular chemical method have been found to self-assemble into nanostructures. Solid-state 13C NMR, solid-state FTIR, and powder X-ray diffraction provided evidence for the β-sheet self-assembly. The overall β-sheet content was as high as 90%. The building blocks had significant impact on the solid-state structure of the resulting polymer. Longer PEO spacers lowered the tendency to self-assemble into antiparallel β-sheets and implicated the existence of PEO-sequestered isolated β-sheets. Differential scanning calorimetry, transmission electron microscopy, and atomic force microscopy confirmed nanostructure formation and microphase separation. The microphase-separated morphology of the polymers contained 20−50 nm peptide domains dispersed in a continuous PEO phase on which was superimposed a 100−150 nm superstructure due to the polymers' polydispersity and multiblock character. Instron measurements suggested that mechanical properties could be modulated by manipulating the building blocks.

Recombinant Spider Silks—Biopolymers with Potential for Future Applications

“…A number of silk-inspired polymers containing blocks of -sheet-forming peptides [GA] n or (A) nn and flexible linkers like PEG [poly(ethylene glycol)] have been reported [94][95][96][97][98]. The Sogah group has published the most comprehensive studies of silk-inspired polymers [99,100]. Multiblock copolymers containing either GAGA tetrapeptides or (A) [4][5][6] peptides coupled with a flexible PEG spacer were prepared, and mechanical properties of the cast films from HFIP or trifluoroethanol solutions were compared.…”

A toolbox of oligopeptide-modified polymers for tailored elastomers

“…Inspired by this example of nature's design principles, the selective formation of onedimensional nanostructures from b-sheet-forming oligopeptides and oligopeptide-modified polymers has been extensively investigated [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] . However, the thermomechanical properties of the corresponding bulk materials have rarely been studied in much detail [29][30][31] . Supramolecular materials from polymers with other types of hydrogen-bonded end groups have frequently been used to obtain thermoplastic elastomers with superior processing behaviour at elevated temperatures [32][33][34][35][36][37][38][39] .…”

Controlled Assembly of Macromolecular β‐Sheet Fibrils

“…However, the fibrillar width was clearly smaller than that of the PEG-[(AG) 3 EG] 20 -PEG conjugates as it could not be measured because, in this case, the grain size of the platinum particles was too large relative to the fibril width to distinguish single fibrils. Single fibrils were difficult to distinguish because of dense coverage of the grid for the CNBr-cleaved PEG-[(AG) 3 EG] 10 -PEG conjugate (Figure 1 d).…”