Genetically Encoded Stimuli-Responsive Biomaterials for Controlled Therapeutic Delivery

Abstract

Current therapeutics on the market are traditionally delivered through oral, parenteral, or pulmonary routes. While these methods allow for easy dosing, most of the therapeutic is not delivered to the targeted disease site, resulting in systemic side effects and the need for multiple doses. The utilization of biomaterials as therapeutic depots bypasses these issues by allowing for localized delivery of large doses of drugs over time. Although there are many published materials for drug delivery, composed of synthetic and/or naturally derived polymers, they struggle with long-term drug release, soft mechanical properties, batch-to-batch variability, biocompatibility, or lack of tunability. Recombinant protein-based polymers, expressed from host cells, address these issues through genetically designed polymers allowing for unprecedented tunability, monodisperse polymers and intrinsic biocompatibility/biodegradability. Genetically encoded polymers are a relatively new material type for controlled delivery, falling behind synthetic materials in terms of available material types and multi-stimuli responsiveness. This thesis focuses on expanding stimuli-responsive recombinant protein-based biomaterial types for controlled delivery of protein therapeutics. We first introduce a shear-thinning and self-healing interpenetrating polymer network (IPN) as an injectable biomaterial for controlled release of multiple protein therapeutics. We next present a method to control protein release following Boolean logic from a single protein chain that utilizes chemical biology tools to autonomously compiling molecular topologies that span 17 possible YES/OR/AND logic outputs in response to protease cues. This method was then extended to control the release of therapeutic proteins, such as growth factors, enzymes, therapeutic nanobodies, de novo-engineered cytokines and fluorescent proteins while maintaining bioactivity as well as incorporating light as a new cue. Further, this method was utilized to design material crosslinks to create multi-stimuli responsive drugamer hydrogels, where bulk degradation and drug release follows Boolean logic. These next-generation genetically encoded controlled release platforms will find a host of applications in precision delivery, regenerative medicine and tissue engineering.