Title: Towards accelerated bioorthogonal drug activation in cancer cells upon independent double-targeting
Language: English
Authors: Schiefer, Andrea 
Qualification level: Diploma
Advisor: Mikula, Hannes  
Assisting Advisor: Fröhlich, Johannes 
Issue Date: 2021
Citation: 
Schiefer, A. (2021). Towards accelerated bioorthogonal drug activation in cancer cells upon independent double-targeting [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2021.96263
Number of Pages: 101
Qualification level: Diploma
Abstract: 
One of the main problems in the field of chemotherapy remains to be the off-target toxicity caused by cancer therapeutics. Many chemotherapeutics do not sufficiently differentiate between healthy cells and cancer cells and therefore damage healthy tissue too. A keyword in that context is drug targeting, which aims for the directed delivery and activation of drugs at the target zone.In general, there are two common drug targeting approaches: Strategies based on tumor-associated receptors (“active targeting”) or based on nanoparticles (“passive targeting”) for anticancer drug delivery. Both strategies have their advantages but also their limitations. Tumor-associated receptors are often also expressed on the surface of healthy cells, and due to their size and polarity, small-molecule ligands are renally excreted and thus mainly accumulate in the kidneys and bladder. Nanoparticles, on the other side, end up to a large part in the filtering organs, the liver and lungs. So, off-target toxicity remains a big challenge in both these targeting approaches.To tackle these limitations, we aim for the development of independent double-targeting as a new concept that combines established targeting strategies and takes advantage of the different pharmacokinetics of nanoparticles and small-molecule ligand conjugates. Due to the combination of bioorthogonal drug active-tion and different biodistribution profiles, we aim to substantially reduce off-target toxicity. The prodrug activation in this strategy is done via a bioorthogonal cleavage reaction between trans-cyclooctenes (TCOs) and tetrazines in a click-to-release approach.Based on preliminary work, confirming the double-targeting approach in cell experiments, the aim of this master thesis was to provide various chemical compounds for further investigation and improvement of the independent double-targeting approach.The main focus of this work was put on the eleven-step synthesis of a drug-TCO conjugate by implementing a superior TCO that shows outstanding properties regarding the efficiency of the bioorthogonal cleavage process. The synthesized TCO was successfully attached to a potent cytotoxin and modified with a C16-carbon chain as lipophilic anchor to facilitate and enhance nanoencapsu-lation. The formation of a dehydrated side-product could be prevented, and the yield was improved by examining different coupling conditions and reversing the order of synthetic steps. The synthesized compound was encapsu-lated in PLGA/PEG nanoparticles and provided for first stability experiments. In addition, three lipophilic C16-modified tetrazines were prepared and nanoencap-sulated. PLGA was conjugated to a fluorescent BODIPY-dye and used for nanoparticle synthesis to allow the monitoring of the nanoparticles in cell studies via fluorescence microscopy. In addition, a fluorescently labeled non-releasing TCO was prepared to enable the visualization of tetrazines by bioorthogonal imaging. A second TCO-drug conjugate was successfully prepared in order to compare the performances of different TCOs in this targeting strategy. The attachment of drug-TCO conjugates and tetrazines to small-molecule ligands will enable various approaches and detailed investigation of independent double-targeting and accelerated drug activation inside cells.
Keywords: Click chemistry; Bioorthogonal chemistry; drug targeting; tetrazines; trans-cyclooctenes
URI: https://doi.org/10.34726/hss.2021.96263
http://hdl.handle.net/20.500.12708/18885
DOI: 10.34726/hss.2021.96263
Library ID: AC16385756
Organisation: E163 - Institut für Angewandte Synthesechemie 
Publication Type: Thesis
Hochschulschrift
Appears in Collections:Thesis

Files in this item:

Fulltext (Version of Record (published version))
Adobe PDF
(9.75 MB)
Embargo. Accessible from 01.01.2099

Page view(s)

23
checked on Dec 2, 2021

Download(s)

10
checked on Dec 2, 2021

Google ScholarTM

Check


Items in reposiTUm are protected by copyright, with all rights reserved, unless otherwise indicated.