Magnetically-driven Therapeutic Agents Delivery System using Iron Oxide Nanocages and Enhancement of Exosome Secretion, a Potential Biological Drug Delivery Carrier

Nano-scale particles have attracted research attention due to their differences in properties such as penetration, circulation, and toxicity compared to bulk materials. This thesis mainly focused on using 20 nm iron oxide nanoparticles as siRNA delivery carriers under the alternating magnetic field and the development of a method to amplify the secretion of 150 nm exosomes from the cells, which could potentially use as a biological drug carrier. Chapter 2 discusses a magnetically driven nanoparticle therapeutic agent delivery system, which efficiently modified the gene expression post-transcriptionally. In this work, we examined whether the caged-shaped 20nm iron oxide nanoparticles (IO-nanocages) can escape from the endosomes when an alternating magnetic field (AMF) is applied and efficiently deliver siRNA to the cytoplasm before digested in lysosomes. Superconducting quantum interference device (SQUID) measurements revealed that 20nm IO-nanocages are dominated by Brownian relaxation as a response to the AMF at 335 kHz. It was observed that the endosomal membrane was ruptured when 335 kHz magnetic field was applied due to the Brownian movement of 20 nm IO-nanocages and released to cytoplasm. After AMF application, targeted gene expression reduced significantly, which revealed the improvement of the siRNA delivery. Chapter 3 explores the magnetic-driven delivery system further by delivering mGluR5 siRNA to the metastatic osteosarcoma cells. It has been studied that type 5 metabotropic glutamate receptor, mGluR5, is required to proliferate metastatic osteosarcoma cells. Therefore, the proliferation of the osteosarcoma cells would decrease when the activity of mGluR5 is silenced. The results elucidated that the mGluR5 siRNAs were successfully delivered by IO-nanocages under AMFs, and the reduction of mGluR5 expression led to cell death. The superparamagnetic properties of IO-nanocages could control the release of siRNA from the IO-nanocages by applying AMFs, resulting in the suppression of targeted gene expression. Chapter 4 describes the enhancement of exosome secretion from the cells by self-assembling synthetic peptide, NapFFK(NBD)Yp. The phosphate group on the peptide will be cleaved by alkaline phosphatase upon entering the cells and self-assemble to form a hydrogel near the endoplasmic reticulum (ER). It has been known that ER stress causes increasing in exosome generation, and we found out that the formation of hydrogel near ER increased cellular stress to amplify the exosome secretion by 4.5-6 folds in MDA-MB231 cells and Bone Marrow Dendritic Cells. This method could improve the application of exosomes as drug delivery carriers, which has limitations due to the low yield of exosome generation from the cells in current research