Exploring the Molecular and Process Determinants of Bottlebrush-based Gene Vectors

Colorado State University, Fort Collins CO

Investigators

Abstract

With the support of the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, Dr. Margarita Herrera-Alonso of Colorado State University will explore the formation of gene-carrying nanoparticles from synthetic macromolecules with a complex architecture. Gene therapy, or the treatment of diseases via delivery of nucleic acids into cells, is in continuous evolution as the search for more efficient delivery strategies moves away from the use of viruses toward the implementation of biocompatible polymers for reasons of safety and cost-efficiency. Nevertheless, the advancement of these polymeric carriers poses a complex materials design challenge, requiring the development of synthetic polymers to minimize carrier toxicity and instability, while maximizing their therapeutic effect. By using modern polymerization methods, the Herrera-Alonso lab will enhance the molecular properties of polymers exhibiting a highly-grafted architecture to explore the roles of structure, chemical reactivity, and the dynamics of the polymer/gene assembly process on the resultant nanoparticle properties. Emphasis will be placed on understanding how these parameters influence gene-carrying nanoparticle stability in biological environments and release of the genetic material. This work aims to establish new design principles for polymer/gene assemblies that will enhance our fundamental understanding of their structure-property relationships and may lead to breakthroughs in the use of gene therapy for the treatment of a wide range of diseases, including cancer, cardiovascular disease, and neurodegenerative diseases. Dissemination of the results from this research will include conferences and publications, as well as through educational and outreach efforts targeted at students ranging from high school to graduate levels. These outreach activities will focus on local high school students who are low-income and potentially the first-generation to pursue post-secondary education. The Herrera-Alonso group seeks to understand the roles of molecular architecture, chemical reactivity, and the kinetics of self-assembly and siRNA complexation on the formation of nanoplexes from bottlebrush polymers. This project will employ bottlebrush block copolymers equipped with environmentally-responsive moieties to build both core- and interlayer-complexed nanoplexes with siRNA. This will be achieved by using a combination of atom transfer radical polymerization, reversible addition-fragmentation chain transfer polymerization, and click chemistry to precisely control the molecular properties of the building blocks including charge density and hydrophobicity, in addition to high-energy mixing methods to control assembly and complexation kinetics. Nanoplexes will be evaluated in terms of their colloidal stability, their responsiveness to an acidic environment, and their ability to enhance endosomal escape. The proposed research will advance our fundamental understanding of polymer assembly and siRNA complexation kinetics and provide critical insight into the factors that enhance control over the final nanoparticle properties. Leveraging the ample physicochemical parameter space uniquely accessible to bottlebrush copolymers with their self-assembly kinetics, will lead to an informed design of gene carriers with far-reaching therapeutic effects. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.