Steven Narum
BME PhD Defense Presentation
Date: 2024-07-30
Time: 1:00 PM to 3:00 PM
Location / Meeting Link: Atwood 316 https://emory.zoom.us/j/91676986251
Committee Members:
Khalid Salaita, Ph.D.; Hanjoong Jo, Ph.D.; Yonggang Ke, Ph.D.; Julie Champion, Ph.D.; Krishnendu Roy, Ph.D.
Title: Rational Design of a Modular Endosomal Escape Platform to Improve Cytosolic Delivery of Nucleic Acids
Abstract:
Endocytosis has long served as a major bottleneck toward nucleic acid delivery as this class of drugs remain trapped within endosomes. Current research trends to overcome endosomal entrapment provide varied success; however, active delivery agents such as endosomal escape peptides (EEP) have emerged as a prominent strategy to improve cytosolic delivery. Yet, EEPs have poor selectivity between endosomal membranes and cellular membranes, leading to toxicity in clinical trials. In this dissertation, I characterize and optimize a pH triggerable trojan horse gene therapeutic that provides a smart ASO release with endosomal acidification and selective membrane disruptive activity. We discovered that an i-Motif duplex undergoes a pH-mediated structure-switch to trigger release of an antisense drug. I further explore cellular cues and learn that nucleases are important in mediating this delivery. Additionally, I explore the application of fluorescence lifetime imaging microscopy (FLIM) to study and visualize the subcellular localization and degradation of spherical nucleic acids (SNAs). I discovered that PS-modified backbones, even in a SNA construct, vastly improve the stability and resistance to nucleases; however, dithiol modifications do not benefit stability nearly to the same extent despite increased thiol-displacement resistance. We show that FLIM measurements are sensitive to the initial stages of SNA dissociation and is a powerful tool to characterize intracellular trafficking. Lastly, I develop the foundation for a biocompatible nanoparticle platform that is clinically viable and therapeutically active. Overall, by addressing current limitations in drug delivery, this work will advance nanomedicine as a whole and provide new techniques for developing smart nanotechnologies and overcoming intracellular barriers.
