Abstract
Elastin-like polypeptides (ELPs) are promising candidates for fabricating tissue-engineering scaffolds that mimic the extracellular environment of elastic tissues. We have developed a “double-hydrophobic” block ELP, GPG, inspired by non-uniform distribution of two different hydrophobic domains in natural elastin. GPG has a block sequence of (VGGVG)5-(VPGXG)25-(VGGVG)5 that self-assembles to form nanofibers in water. Functional derivatives of GPG with appended amino acid motifs can also form nanofibers, a display of the block sequence’s robust self-assembling properties. However, how the block length affects fiber formation has never been clarified. This study focuses on the synthesis and characterization of a novel ELP, GPPG, in which the central sequence (VPGVG)25 is repeated twice by a short linker sequence. The self-assembly behavior and the resultant nanostructures of GPG and GPPG were when compared through circular dichroism spectroscopy, atomic force microscopy, and transmission electron microscopy. Dynamic rheology measurements revealed that the nanofiber dispersions of both GPG and GPPG at an extremely low concentration (0.034 wt%) exhibited solid-like behavior with storage modulus G′ > loss modulus G” over wide range of angular frequencies, which was most probably due to the high aspect ratio of the nanofibers that leads to the flocculation of nanofibers in the dispersion.
Highlights
Self-assembling peptides are promising candidates for the fabrication of tissue-engineering scaffolds, because their nanostructures resemble those of extracellular matrix (ECM) proteins, and their physicochemical and biological properties can be tailored by designing its amino acid sequences [1,2,3,4]
Elastin-like polypeptides (ELPs), which contain repetitive amino acid sequences that are found in elastin, an ECM protein abundant in elastic tissues, are among the self-assembling polypeptides that have been intensively explored for biomedical applications [5,6,7,8]
Various functional amino acid motifs, including crosslinkable [30], cell binding [29], and silver binding [31] sequences, can be fused to the C-terminus of GPG without hampering its fiber-forming abilities, demonstrating the robust self-assembling characteristics of this block sequence. It has never been clarified whether the block length exerted influence on the self-assembly of this double-hydrophobic polypeptide, despite the fact that the block length is an important parameter in the self-assembly processes of block copolymers [19,25,34]
Summary
Self-assembling peptides are promising candidates for the fabrication of tissue-engineering scaffolds, because their nanostructures resemble those of extracellular matrix (ECM) proteins, and their physicochemical and biological properties can be tailored by designing its amino acid sequences [1,2,3,4]. Various functional amino acid motifs, including crosslinkable [30], cell binding [29], and silver binding [31] sequences, can be fused to the C-terminus of GPG without hampering its fiber-forming abilities, demonstrating the robust self-assembling characteristics of this block sequence. It has never been clarified whether the block length exerted influence on the self-assembly of this double-hydrophobic polypeptide, despite the fact that the block length is an important parameter in the self-assembly processes of block copolymers [19,25,34].
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