BORIS Theses

BORIS Theses
Bern Open Repository and Information System

Formulation and characterization of siRNA embedded nanoparticles for pulmonary delivery

Zimmermann, Christoph Martin (2022). Formulation and characterization of siRNA embedded nanoparticles for pulmonary delivery. (Thesis). Universität Bern, Bern

22zimmermann_cm.pdf - Thesis
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Advancing existing or developing novel nanoparticle carrier systems is a crucial part of successful nucleic acid delivery for therapeutic purposes. The overall aim of nanoparticle formulations is to deliver their cargo to the site of action. During this procedure, nanoparticles need to show qualities to be internalized into the cell and release their cargo. Dependent on the application route and prior to cell uptake, nanoparticles can be transferred into a form of administration that improves conformation and leads to long-term storage stability. The aim of this thesis is to identify various small interfering RNA (siRNA)-nanoparticle formulations as drug delivery systems with potential to target the lungs (Chapter I + II). Nanoparticles carrier systems comprised of polymers, lipids or a hybrid combination encapsulating nucleic acids and were formed using the concept of microfluidic mixing. The thesis can be separated into two main parts. The first part addresses the common dilemma of the endosomal escape problem by improving existing polymers through chemical modification (Chapter III), synthesizing a novel amphiphilic polymer (Chapter IV) and forming hybrid lipid polyplex nanoparticles (Chapter V). The second section focuses on the development of a spray-drying approach (Chapter VI) and the long-term storage under various conditions (Chapter VI) for siRNA-lipid nanoparticles (LNPs) based on an adapted Onpattro® formulation. The endosomal release problem of polymeric nanoparticles was tackled looking at physicochemical nanoparticle characterization and in vitro performance assessment. Throughout Chapters III - V, sizes of 100 – 200 nm were reached, the zeta potential was kept neutral to positive, and the encapsulation efficiency of siRNA showed values > 90% resulting in an improved in vitro knockdown performance (> 50%) in comparison to polyethylene imine (PEI) polyplexes or triblock copolymer polyplexes cores. The establishment of a spray drying platform for LNPs (Chapter VI) and subsequent drying for storage stability (Chapter VII) resulted in spray dried powders that maintained LNP integrity and stability by loosing up to 15% of siRNA and lipid content. The aerodynamic properties showed ideal characteristics for pulmonary delivery with sizes of 3 μm. The in vitro performance reached knockdown levels of > 95% and a house keeping gene silencing of > 50% was established ex vivo in human precision cut lung slices. In conclusion, this thesis should give an overview of several non-viral siRNA nanoparticles as nucleic acid delivery systems that on the one hand improve the endosomal escape problem of polymeric nanoparticles, and on the other hand are established for pulmonary delivery through a spray drying method.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 12 December 2022
Subjects: 500 Science > 540 Chemistry
500 Science > 570 Life sciences; biology
Institute / Center: 08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)
Depositing User: Hammer Igor
Date Deposited: 08 Feb 2024 09:52
Last Modified: 08 Feb 2024 23:25

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