DNA nanostructures have enjoyed wide interest for their potential as diagnostic and/or therapeutic platforms. One attractive feature is the precise geometric control over shape and site-specific decoration with ligands. In collaboration with groups of Ju Hee Ryu and Ick Chan Kwon at KIST, David Mooney at Wyss Institute and Harvard SEAS, and Cathy Wu at DFCI, our current focus is on DNA-origami pegboards that can present exact stoichiometries and spartial arrangements of ligands, such as CpG oligonucleotides, for immune polarization of dendritic cells. In this way, we hope to enhance vaccines against cancer.
Image credit Chris Wintersinger and Yang (Claire) Zeng
Schematic of DNA origami cancer vaccine containing CpG (green) as adjuvant, OVA protein (blue) as model antigen and Cy5 dye (pink) as tracer.
A challenge for in vivo deployment of DNA nanostructures is their susceptibility to denaturation and degradation under physiological conditions. To address this issue, we have developed PEGylated oligolysine as a material than can electrostatically coat DNA nanostructures and protect them from in vivo destruction. We also determined that further crosslinking with glutaraldehyde can increase the nuclease resistance of DNA nanostructures by another two to three orders of magnitude. Availability of these strategies suggests that DNA nanostructures may prove suitable for deployment against a wide range of clinical problems.
image credit Frances Anastassacos
DNA nanostructure (DN) fabrication process and resultant increase in resistance to nuclease degradation. DNs are first coated with PEGylated oligolysine (K10P-DNs) through electrostatic adhesion. Subsequent addition of glutaraldehyde covalently cross-links oligolysine amines and reduces dissociation of the lysine coating.
Ponnuswamy N, Bastings MMC, Nathwani B, Ryu JH, Chou LYT, Vinther M, Li WA, Anastassacos FM, Mooney DJ, Shih WM. Oligolysine-Based Coating Protects DNA Nanostructures from Low-Salt Denaturation and Nuclease Degradation. Nat Commun. 8, 15654, 2017. [zip]
Anastassacos FM*, Zhao Z*, Zeng Y, Shih WM. Glutaraldehyde Cross-Linking of Oligolysines Coating DNA Origami Greatly Reduces Susceptibility to Nuclease Degradation. J Am Chem Soc. 142, 3311–3315, 2020. [zip]