Artificial virus-like capsids decorated with ribonuclease S (RNase S) on their exterior were constructed by the self-assembly of βannulus-S-peptide and the interaction between S-peptide moiety and Sprotein. The β-annulus-S-peptide was synthesized by native chemical ligation of β-annulus-SBz peptide with Cys-containing S-peptide that self-assembled into artificial virus-like capsids of approximately 47 nm in size. Reconstruction of RNase S on the artificial virus-like capsids afforded spherical assembly attached small spheres on the surface, which retained ribonuclease activity.

Genetic engineering of economically important traits in plants is an effective way to improve global welfare. However, introducing foreign DNA molecules into plant genomes to create genetically engineered plants not only requires a lengthy testing period and high developmental costs but also is not well-accepted by the public due to safety concerns about its effects on human and animal health and the environment. Here, we present a high-throughput nucleic acids delivery platform for plants using peptide nanocarriers applied to the leaf surface by spraying. The translocation of sub-micrometer-scale nucleic acid/peptide complexes upon spraying varied depending on the physicochemical characteristics of the peptides and was controlled by a stomata-dependent-uptake mechanism in plant cells. We observed efficient delivery of DNA molecules into plants using cell-penetrating peptide (CPP)-based foliar spraying. Moreover, using foliar spraying, we successfully performed gene silencing by introducing small interfering RNA molecules in plant nuclei via siRNA-CPP complexes and, more importantly, in chloroplasts via our CPP/chloroplast-targeting peptide-mediated delivery system. This technology enables effective nontransgenic engineering of economically important plant traits in agricultural systems.

The decoration of a peptide-based artificial viral capsid with gold nanoparticles (AuNPs) is reported. β-Annulus GGGCG-bearing peptide as a binding site of AuNPs self-assembled into nanocapsules with a diameter of 50 nm. The addition of AuNPs to the peptide nanocapsules afforded relatively uncontrolled assemblies of AuNPs. In contrast, the self-assembly of AuNP-peptide conjugates afforded, after dialysis, controlled assemblies of AuNPs with sizes of 30-60 nm. ζ-Potential measurements revealed that the surface of the artificial viral capsid self-assembled from β-annulus peptide was coated with AuNPs.

In order to construct artificial viral capsids bearing complementary dimeric coiled-coils on the surface, a β-annulus peptide bearing a coiled-coil forming sequence at the C-terminus (β-annulus-coiled-coil-B) was synthesized by a native chemical ligation of a β-annulus-SBn peptide with a Cys-containing coiled-coil-B peptide. Dynamic light scattering (DLS) measurements and transmission electron microscopy (TEM) images revealed that the β-annulus-coiled-coil-B peptide self-assembled into spherical structures of about 50 nm in 10 mM Tris-HCl buffer. Circular dichroism (CD) spectra indicated the formation of the complementary coiled-coil structure on the spherical assemblies. Addition of 0.25 equivalent of the complementary coiled-coil-A peptide to the β-annulus-coiled-coil-B peptide showed the formation of spherical assemblies of 46 ± 14 nm with grains of 5 nm at the surface, whereas addition of 1 equivalent of the complementary coiled-coil-A peptide generated fibrous assemblies.