Author Type

Graduate Student

Date of Award

Fall 11-18-2025

Document Type

Thesis

Publication Status

Version of Record

Submission Date

November 2025

Department

Chemistry and Biochemistry

Degree Name

Master of Science (MS)

Thesis/Dissertation Advisor [Chair]

Predrag Cudic

Abstract

A promising strategy that could be used to treat many central nervous system (CNS) diseases, including Parkinson’s disease, Alzheimer’s disease and brain cancer, is through gene silencing by short interfering RNAs (siRNA). siRNA induces gene silencing by targeting complementary mRNA for degradation. However, a key challenge in the development of siRNA-based therapies for the CNS diseases is their transport across the blood–brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). To facilitate the transport of siRNA across the BBB and BCSFB we have designed a siRNA delivery system based on the 17-mer naturally occurring cyclic peptide odorranalectin (OL) carrying multiple positive charges. Our group has shown previously that OL preferentially binds to the L-fucose and to a lesser degree D-galactose and N-acetyl-D-galactosamine, which are widely distributed on the olfactory epithelium of nasal mucosa, suggesting a possibility for intranasal delivery. As a proof of principle, we have prepared a series of positively charged OL-based peptides. This was achieved by incorporating poly arginine sequences (poly-R) of various lengths, as well as the sequence of the TAT peptide (YGRKKRRQRRR), derived from the human immunodeficiency virus TAT protein, into the OL scaffold. We hypothesized that the cationic sequence of OL will bind negatively charged siRNA, while the carbohydrate-binding sequence of OL will facilitate nose-to-brain transport of the siRNA/cationic-OL complex. The synthesized cationic peptides were tested for SiRNA binding using Circular Dichroism (CD) spectroscopy, and gel electrophoresis, while Isothermal Titration Calorimetry (ITC) was used to evaluate if addition of cationic peptides to OL N-terminal side doesn’t hinder the ability of OL to bind glycoproteins.

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