Supramolecular self assembly of nanodrill-like structures for intracellular delivery

Abstract

Despite recent advances in the supramolecular assembly of cell-penetrating peptide (CPP) nanostructures, the tuning of size, shape, morphology and packaging of drugs in these materials still remain unexplored. Herein, through sequential ligation of peptide building blocks, we create cell-penetrating self-assembling peptide nanomaterials (CSPNs) with the capability to translocate inside cells. We devised a triblock array of Tat [HIV-1 derived transactivator of transcription] based CPPs, conjugated to up to four Phenylalanine (Phe) residues through an amphiphilic linker, (RADA). We observed that the sequential addition of Phe leads to the transition of CSPN secondary structures from a random coil, to a distorted α-helix, a β-sheet, or a pure α-helix. This transition occurs due to formation of a heptad by virtue of even number of Phe. Atomic force microscopy revealed that CSPNs form distinct shapes reminiscent of a "drill-bit". CSPNs containing two, three or four Phe, self-assemble into "nanodrill-like structures" with a coarse-twisted, non-twisted or fine-twisted morphology, respectively. These nanodrills had a high capacity to encapsulate hydrophobic guest molecules. In particular, the coarse-twisted nanodrills demonstrate higher internalization and are able to deliver rapamycin, a hydrophobic small molecule that induced autophagy and are capable of in vivo delivery. Molecular dynamics studies provide microscopic insights into the structure of the nanodrills that can contribute to its morphology and ability to interact with cellular membrane. CSPNs represent a new modular drug delivery platform that can be programmed into exquisite structures through sequence-specific fine tuning of amino acids.

Advances in intracellular delivery through supramolecular self-assembly of oligonucleotides and peptides

“…On self-assembling, hydrophilic residues of amino acids are located toward the exterior water phase while hydrophobic residues are buried in the core, contributing to the unique structures of β sheeted materials that are effective for small molecule or gene delivery applications (Figure 7A) 108. The first β sheet nanomaterial, RADA 16, has been utilized for drug delivery 109,110, regenerative medicine (neural stem cell differentiation) 111, in vivo brain damage repair and bone regeneration 112,113. The SAPs that form the nanostructures with a high aspect ratio, like ribbons, fibrils, and fibers, with varied numbers of β sheets in the final structures.…”

“…Short aromatic peptides such as FF, FY, Fmoc-FF, and Nap-FF have shown that the incorporation of those peptide can cause self-assembly of peptides via strong aromatic π-π stacking 145. Recently, Ashwanikumar et al reported that the structures of self-assembled peptide-based nanomaterials can be manipulated from a random coil, a distorted α-helix, a β-sheet, or to a pure α-helix by changing the number of phenylalanine in the sequence 109. The twisted drill-like nanostructures showed the highest internalization as compared to the other regular cylindrical counterparts in vitro and in vivo .…”

“…Engineering supramolecular self-assembly of either DNA, RNA or peptide can lead to delivery of a wide range of cargos with favorable circulation, biodistribution, cellular uptake, and efficacy. Amphiphilicity introduced to initiate the self-assembling process has allowed for encapsulation of hydrophobic small molecules 109. To achieve the target-specific delivery, it was introduced in the self-assembled delivery systems either to have targeting ligands on the surface 99, or to change their conformations in response to external stimuli 127,135.…”

Supramolecular nanoscale drug-delivery system with ordered structure

“…A new example has employed Tat peptides conjugating with a RADA sequence to obtain supramolecularly assembled nanodrills for the intracellular delivery of hydrophobic therapeutics (Fig. 2 ) [ 73 ]. In this design, the cell-penetrating peptide (CPP) Tat derived from HIV1 donates a hydrophobic sequence, providing a high capacity for biological membrane penetration [ 74 ]; a RADA sequence modified with various phenylalanine (Phe, F) residues provides a supramolecular complex driving force with a β-sheet formation and π–π stacking.…”

Modular design and self-assembly of multidomain peptides towards cytocompatible supramolecular cell penetrating nanofibers

“…Inspired by recent advances in peptide self-assembly and cell penetrating macromolecules, in particular self-assembled cell penetrating peptides, [25][26][27][28][29][30][31] we have developed a new class of peptide assemblies with intrinsic cell penetrating activity, termed supramolecular cell penetrating nanobers (SCPNs). [32][33][34][35] SCPNs are generated through the self-assembly of de novo designed cationic multidomain peptides (MDPs) with a general sequence of K x (QW) 6 (K: lysine, Q: glutamine; W: tryptophan).…”