Nanoscale click-reactive scaffolds from peptide self-assembly

Abstract

Although previous studies have produced peptides that can both form amyloid fibrils and undergo "click"-type reactions, this is the first example of amyloid fibrils that can undergo such a reaction after they have been formed. Our approach has the advantage that self-assembly takes place before click functionalization rather than pre-functionalised building blocks self-assembling. Therefore, the molecules used to functionalise the fibril do not themselves have to be exposed to harsh, amyloid-forming conditions. This means that a wider range of proteins can be used as ligands in this process. For instance, the fibrils can be functionalised with a green fluorescent protein that retains its fluorescence after it is attached to the fibrils, whereas this protein loses its fluorescence if it is exposed to the conditions used for aggregation.

Amyloid self‐assembling peptides: Potential applications in nanovaccine engineering and biosensing

“…In this study, the CuAAC ) “click” reaction was performed between an alkyne‐TTR (85–95) derivative and azide‐functionalized fluorophores (fluorescein and GFP). The resulting assemblies were fluorescent, thus confirming the accessibility of the alkyne group on the surface of the amyloid scaffold and the soft conditions that preserved functionality upon conjugation . Other type of postassembly functionalization were also investigated, including the native chemical ligation for the functionalization of peptide nanotubes, and the sortase A (srtA) mediated conjugation to immobilize molecules onto amyloid fibrils assembled from TTR, among many others as recently and comprehensively reviewed by Luo and colleagues .…”

“…This preassembly approach has been extensively utilized, as exemplified with the Q11 peptide (QQKFQFQFEQQ), which has been investigated for the development of nanovaccines . However, the preassembly strategy can lead to misassembly and loss of functionality . Moreover, this approach is challenging to implement when bulky functional moieties, such as large globular protein, are connected to the self‐assembling peptides sequence, as self‐recognition can be hindered.…”

“…However, the conjugation of a large protein with a short self‐assembling peptide could interfere with the process of amyloid formation. For instance, Guttenplan et al recently demonstrated that peptide functionalization with complex and large biomolecules, such as globular proteins, prior to self‐assembly can lead to a loss of functionality upon self‐assembly or, more frequently, can preclude self‐assembly . In this context, Q11 self‐assembling peptide bearing a p‐nitrophenyl phosphonate (pNP) ligand was synthesized by reacting the N‐terminal cysteine side chain of Q11 with maleimido‐penta(ethylene glycol)‐ethyl‐p‐nitrophenyl phosphonate.…”

Modifying the surface of peptide nanofibers utilizing a thiol‐thioester exchange

“…[ 15 ] Additionally, the orthogonal copper(I)‐catalyzed azide‐alkyne and thiol‐ene covalent click reactions have been used to fluorescently label self‐assembled peptide fibers after peptides containing either azide and/or thiol functional groups were allowed to assemble. [ 16,17 ] Some examples of other post‐assembly modification methods have utilized noncovalent interactions to functionalize peptide nanofibers. Biomolecular recognition using either Watson‐Crick base pairing between peptide nucleic acid modified fibers with a crosslinking oligonucleotide strand or protein‐ligand interactions between mannose‐modified fibers with the lectin concanavalin A were used to control hydrogel elasticity.…”

Controlling self-assembling and tumor cell-targeting of protein-only nanoparticles through modular protein engineering

“…Proteins and peptides, over other materials commonly explored as drug delivery systems, offer high structural and functional versatility easily regulatable by genetic engineering. This flexibility allows generating protein materials non-existing in nature, with novel functions or combinations of them, for appealing applications [2][3][4][5][6][7][8].…”