Bioengineering Graduate Program - MPhil Thesis Presentation - Super-resolution Imaging of DNA / Peptide Assembly

Gene therapy delivers nucleic acids into target cells in the human body, which is specific to a small subset of disease cells and has less damage to other healthy cells compared to classical medicines therapy. Self-assembling protein / peptide-based structural viral mimicry is one kind of vector for gene therapy, which combines the advantages of viral vectors and non-viral vectors and is expected to have high efficiency and low immunogenicity. The assembly of H4K5-HCBzlCBzlH and DNA is an example of such viral mimicry. Its diameter is about 50 nm and it has a spotted surface, therefore it can be called nanoberry. Confocal imaging has been used to study the endocytosis of nanoberry, but the detailed process has not been revealed due to the limited resolution of optical microscopes. Superresolution imaging can break this limit because its resolution in the lateral dimensions can reach 20 to 30 nanometers.

In our experiments, we labeled DNA with YOYO-1 and performed super-resolution imaging on the labeled nanoberry and the loose complex. We showed that single nanoberry particles can be identified and distinguished from the loose complex using super-resolution imaging. The demonstrated results of the endocytosis process of nanoberry and DNA release, suggesting super-resolution imaging technology has the potential to reveal the mechanism underlying the endocytosis process and guide the viral mimicry design with higher gene delivery efficiency.