Superior cell penetration by a rigid and anisotropic synthetic protein

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

Cells utilize natural supramolecular assemblies to maintain homeostasis and biological functions. Naturally inspired modular assembly of biomaterials are now being exploited for understanding or manipulating cell biology for treatment, diagnosis, and detection of diseases. Supramolecular biomaterials, in particular peptides and oligonucleotides, can be precisely tuned to have diverse structural, mechanical, physicochemical and biological properties. These merits of oligonucleotides and peptides as building blocks have given rise to the evolution of numerous nucleic acid- and peptide-based self-assembling nanomaterials for various medical applications, including drug delivery, tissue engineering, regenerative medicine, and immunotherapy. In this review, we provide an extensive overview of the intracellular delivery approaches using supramolecular self-assembly of DNA, RNA, and peptides. Furthermore, we discuss the current challenges related to subcellular delivery and provide future perspectives of the application of supramolecular biomaterials for intracellular delivery in theranostics.

Effect of the Aspect Ratio of Coiled-Coil Protein Carriers on Cellular Uptake

We showed previously that a rigid and fibrous-structured cationic coiled-coil artificial protein had cell-penetrating activity that was significantly greater when compared with a less-structured cell-penetrating peptide. Nanomaterials with anisotropic structures often show aspect-ratio-dependent unique physicochemical properties, as well as cell-penetrating activities. In this report, we have designed and demonstrated the cell-penetrating activity of a shorter cationic coiled-coil protein. An aspect ratio at 4.5:1 was found to be critical for ensuring that the cationic coiled-coil protein showed strong cell-penetrating activity. At an aspect ratio of 3.5:1, the cationic coiled-coil protein showed cell-penetrating activity that was similar to a less-structured short cationic cell-penetrating peptide. Interestingly, at an aspect ratio of 4:1, the cationic coiled-coil protein exhibited intermediate cell-penetrating activity. These findings should aid in the principle design of intracellular drug delivery carriers including coiled-coil artificial proteins, their derivatives, and α-helical cell-penetrating peptides as well as provide a framework for developing synthetic nanomaterials, such as metal nanorods and synthetic polymers.