Chemical modifications of oligonucleotides (ONs) have advanced these molecules towards clinical approvals. On their own, native ONs have poor pharmacokinetic properties, such as rapid degradation by nucleases and poor cell uptake, which limit their potential therapeutic applications. Chemical modifications of ONs can increase their stability, alter their interactions with cells, and couple them with other therapeutic agents. Additionally, the arrangement of ONs in a spherical nucleic acid (SNAs) architecture—a dense radial arrangement of ONs about a nanometer sized core—further augments their therapeutic properties. SNAs have been used for gene regulation, intracellular detection, and immunotherapy applications, among others. This thesis explores how controlling the chemical structure of ONs within SNA architectures can be a powerful tool for controlling their therapeutic efficacy. In Chapter 1 an automated solid-phase synthesis of positively charged guanidinium linked DNA (DNG) is developed, which uses a commercially available synthesizer to increase scale and rate while circumventing the toxic reagents used to date. The new synthetic approach allows for exploration of this ON modification in a biological context, where rapid cellular uptake and no apparent toxicity are observed. In Chapter 2, the effects of oligonucleotide charge on SNA properties are explored by introducing DNG modifications into the ON shell. Improved cellular uptake is observed and believed to be due to a pathway influenced by the chemical structure of the modified ON. In Chapter 3, traceless conjugation is used to link ONs with peptide antigens in an effort to improve the immunostimulatory potency of the SNAs compared to other commonly used linkers. The traceless conjugation chemistry is further explored in Chapter 4 and used to show that subtle chemical changes to the linker structure can alter significantly the rates of antigen release. Rapid rates of antigen release translate to faster and greater antigen presentation and may account for the improved immune stimulation. Taken together, these findings illustrate the importance of understanding and manipulating the chemistry of the ONs that comprise SNA constructs and will lead to the translation of new and improved ON therapeutics.

Creator

• Skakuj, Kacper

DOI

• https://doi.org/10.21985/n2-z70f-f556

Subject

• Chemistry

Language

• en

Alternate Identifier

• etdadmin_upload_769294
• http://dissertations.umi.com/northwestern:15317

Date created

• 2020-01-01

Resource type

• Dissertation

Rights statement

• In Copyright