DNA-functionalized colloidal crystals for macromolecular encapsulation

Abstract

Novel DNA-based structures with the ability to encapsulate nanoscale molecules, such as proteins, can be applied to a wide range of areas, including reaction fields and micro/nano drug carriers. DNA-functionalized nanoparticle (DNA-NP) colloidal crystals have emerged as a new class of programmable DNA-based structures harboring metal nanoparticles with improved mechanical properties. The encapsulation of guest molecules into empty spaces in lattice structures is theoretically possible. However, due to the lack of a strategy for versatile encapsulation of guest molecules, the feasibility of nanoscale encapsulation by DNA-NP crystals is unclear. In this study, we developed DNA-functionalized gold nanoparticle (DNA–AuNP) crystals with tunable interparticle spacing for molecular encapsulation. We demonstrated that the modification of DNA–AuNP crystals with functional moieties, that is, biotin molecules, was effective in retaining molecules in the crystals. The crystallinities before and after encapsulation of the molecules were confirmed using small-angle X-ray scattering. We also succeeded in encapsulating CRISPR/Cas9 ribonucleoproteins into DNA–AuNP crystals by harnessing their affinity for target molecules. These findings demonstrated the potential use of metal–DNA hybrid crystals as carriers for direct protein delivery via biolistic bombardment. Thus, this study provides an attractive strategy for creating a new class of DNA-based structures for macromolecular encapsulation, and an alternative research direction toward colloidal crystal engineering using DNA.