Sub-20 nm Stable Micelles Based on a Mixture of Coiled-Coils: A Platform for Controlled Ligand Presentation

Abstract

Ligand-functionalized, multivalent nanoparticles have been extensively studied for biomedical applications from imaging agents to drug delivery vehicles. However, the ligand cluster size is usually heterogeneous and the local valency is ill-defined. Here, we present a mixed micelle platform hierarchically self-assembled from a mixture of two amphiphilic 3-helix and 4-helix peptide-polyethylene glycol (PEG)-lipid hybrid conjugates. We demonstrate that the local multivalent ligand cluster size on the micelle surface can be controlled based on the coiled-coil oligomeric state. The oligomeric states of mixed peptide bundles were found to be in their individual native states. Similarly, mixed micelles indicate the orthogonal self-association of coiled-coil amphiphiles. Using differential scanning calorimetry, fluorescence recovery spectroscopy, and coarse-grained molecular dynamics simulation, we studied the distribution of coiled-coil bundles within the mixed micelles and observed migration of coiled-coils into nanodomains within the sub-20 nm mixed micelle. This report provides important insights into the assembly and formation of nanophase-separated micelles with precise control over the local multivalent state of ligands on the micelle surface.

Multicomponent peptide assemblies

“…Multivalent protein display on coiled coil nanoparticles were also reported by Xu and coworkers. 506 The Xu group had developed three helix coiled coils derived from peptide-(PEG)-lipid conjugates. These three-helix coiled coil amphiphiles were shown to self-assemble into multimeric structures and stable spherical particles that have potential as biological nanocarriers.…”

“…Figure reproduced with permission from J. Ang, D. Ma, B. T. Jung, S. Keten and T. Xu, Biomacromolecules , 2017, 18 , 3572–3580. 506 © 2017 American Chemical Society.…”

Molecular Simulations of PEGylated Biomolecules, Liposomes, and Nanoparticles for Drug Delivery Applications

“…In addition, coiled coils can self-assemble to mechanically rigid protein fibers and thus have been synthesized for drug delivery applications as templates to promote the assembly of other molecules [ 87 , 88 ]. To increase their solubility and stability, PEGylated coiled coils have been experimentally synthesized by the Klok group [ 89 , 90 , 91 , 92 , 93 ], the Kros group [ 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 ], and the Xu group [ 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 ], showing membrane fusion and micelle assembly modulated by peptide sequence, PEG size and density, which have been theoretically complemented by simulations.…”

“…They also found the high helicity and stability of coiled coils grafted with low-molecular weight PEG chains [ 117 ], and the extended structure of PEG chains grafted to helix micelles [ 110 ]. In particular, PEGylation influences the micelle size and stability, which is interpreted by a competition between the entropy of PEG conformations in the assembled state [ 111 , 118 ]. Recently, they performed both all-atom and CG simulations of PEGylated coiled coils composed of three or four helices, showing the formation of self-assembled micelles and the effect of the coiled coil oligomeric state on micelle size and stability [ 119 ].…”

Designing Sub-20 nm Nanocarriers for Small Molecule Delivery: Interplay among Structural Geometry, Assembly Energetics, and Cargo Release Kinetics

“…4,5,[35][36][37][38][39] Additionally, 3HM has been shown to possess favorable in vivo biodistribution, pharmacokinetics, and accumulation in orthotopically xenografted brain tumors. 4,5,[35][36][37] Energetic contributions from each of the comprising components (peptide, 37,40 polymer, 37,39 and alkyl chains 36 ) have been systematically studied. Building upon this well-rounded background knowledge, 3HM becomes a great model system to investigate nanomaterial-drug co-assembly.…”