Sprecher
Beschreibung
DNA origami is a powerful bottom-up technique that leverages specific Watson-Crick-Franklin base pairing to build complex and reproducible nanostructures with precise size and shape control. These biocompatible nanostructures offer diverse applications in biomedicine and nanobiotechnology, such as therapeutic delivery, biosensing, and biomimetics. However, many of these applications do normally require origamis to be chemically equipped with functional moieties.
Here, we present a versatile strategy to fold and chemically modify DNA origami exploiting the reactivity of the polycation spermine-azide (SpAz). SpAz facilitates DNA origami folding and enables its subsequent conjugation via Strain-Promoted Alkyne-Azide Cycloaddition (SPAAC) with three dibenzocyclooctyne (DBCO)-functionalized molecules: a fluorophore (Cy5), polyethylene glycol (PEG), and a phosphatidylethanolamine (PE) tag.
Successful SpAz-mediated folding of DNA origami was verified by gel electrophoresis (GE), dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electron microscopy. Cy5 conjugation resulted in a high functionalization degree, confirmed by UV-Vis spectroscopy, GE, and confocal microscopy. PEG modification increased the hydrodynamic diameter, height, and volume of the origamis, as shown by DLS and AFM. Interestingly, the incorporation of PEG altered the nanomechanical properties of the origamis, leading to a decrease in Young’s modulus, as verified by nanoindentation measurements.
Additionally, SPAAC functionalization was exploited to mediate the attachment of SpAz-folded origamis to giant unilamellar vesicles (GUVs), which serve as biomimetic models for cell membranes. Confocal microscopy confirmed successful binding to PE-DBCO-containing GUVs. No attachment was observed in the absence of PE-DBCO, confirming that the process was SPAAC-mediated. Heterovalent functionalization with both Cy5 and PE was also demonstrated, with a remarkable influence of the stoichiometric ratio between Cy5 and SpAz.
Our study introduces a facile strategy for folding and functionalizing DNA nanostructures by leveraging the reactive polyamine SpAz. This approach enables the efficient conjugation of diverse functional tags while preserving origami structural integrity, making it adaptable for various applications in bioimaging, therapeutic delivery, and biomimetics. By providing a straightforward and versatile method, this work expands the potential of DNA origami and DNA nanotechnology for the development of functional nucleic acid-based materials.
