From Peptides to Silk-Inspired Proteins: Self-Assembling Systems for Functional Biomaterials

Abstract

Peptides and proteins, though both composed of amino acids, differ significantly in their structural and functional complexity. Peptides are generally shorter chains of amino acids and typically adopt simple secondary structures, such as α-helices or β-sheets. However, they rarely develop the intricate tertiary and quaternary structures that are characteristic of proteins. Proteins, which consist of longer polypeptide chains, exhibit complex folding patterns stabilized by various interactions, including hydrogen bonds, disulfide linkages, and hydrophobic interactions. This structural complexity allows proteins to perform highly specialized biological functions, such as enzymatic catalysis, signal transduction, and structural support.

Both peptides and proteins have the ability to undergo self-assembly, forming higher-order structures through noncovalent interactions such as hydrogen bonding, electrostatic forces, and hydrophobic interactions. In particular, peptide functional assemblies also serve various roles, such as drug delivery, biosensors, intracellular modulation, and structural scaffolds. Depending on their sequence, they can exhibit antioxidant, antimicrobial, receptor-targeting, or enzyme-inhibitory properties. Peptides also play a crucial role in developing biomaterials like hydrogels and nanomaterials for various applications in both biomedical and engineering fields. Researchers have explored the design of peptide-based hydrogels, nanoparticles, and scaffolds that can mimic extracellular matrices, facilitating cell growth and tissue regeneration. The combination of peptides with other biomaterials has also led to innovative solutions for controlled drug release and antimicrobial coatings.

In proteins, self-assembly is crucial for biological function, as exemplified by the formation of multiprotein complexes. These complexes are essential for many biological processes, including structural scaffolds, cellular signaling and immune responses. Among structural protein assemblies, silk has gained significant attention due to its exceptional mechanical properties, biocompatibility, and sustainability. Silk fibers adopt a hierarchical structure comprising crystalline β-sheet domains interspersed with amorphous regions. This unique arrangement imparts superior strength, elasticity, and toughness, making silk a versatile material for a wide range of applications. Traditionally used in textiles, silk has recently emerged as a promising biomaterial building block in the medical field. Its ability to form various material formats, including fibers, films, and hydrogels, has enabled advancements in drug delivery, wound healing, and regenerative medicine.

The expanding field of recombinant silk and peptide engineering holds tremendous promise for sustainable bioengineering and biomaterial development. Advances in synthetic biology and genetic engineering have enabled the mass production of silk-inspired proteins and functional peptides using microbial expression systems. This progress not only reduces reliance on traditional silk production but also expands the possibilities for engineering novel biomaterials with tailored properties. As research in this field continues, the potential applications of silk materials and functional peptides in healthcare, material science, and environmental sustainability are expected to grow, paving the way for groundbreaking innovations in biotechnology and medicine.