Multicompartmental Biomaterials via Electrohydrodynamic Co-jetting.

Abstract

The synthesis and theranostic applications of biodegradable anisotropic materials are described in this dissertation. Precise nano- and micro-scale control of the architecture of biodegradable polymeric materials is highly desirable for improved versatility and performance of biomedical devices such as drug release systems, biomedical coatings and multiplexed bioassays. Along with traditional attributes such as size, shape and chemical structure of polymeric micro-objects, control over material distribution, or selective compartmentalization has been shown to be increasingly important for maximizing functionality and efficacy. The simplest example of a compartmentalized micro-structure is a ‘Janus’ sphere, comprising of two distinct hemispheres made of different materials. Such novel particle geometries enable independent control of key parameters, such as chemical composition, surface functionalization, biological loading, shape, and size for each compartment, thereby effectively mimicking many of nature’s complex architectures. In this dissertation, the fabrication of multicompartmental architectures made from biodegradable polymers, specifically poly(lactide-co-glycolide) (PLGA) is demonstrated. To accomplish this, we employed ‘electrohydrodynamic co-jetting’, whereby the interface between two or more polymer solutions is sustained as they are flown through a side-by-side capillary system. Application of an electric field results in the formation of an electrospray, and solvent evaporation results in particle (or fiber) formation. By controlling over solution and process parameters, a vast repertoire of shapes and sizes of anisotropic objects such as spheres, fibers, discs, rods, and cylinders was formulated. Compositional anisotropy is also introduced in particles and fibers by means of incorporation of functional materials such as magnetite nanoparticles, and stimuli responsive hydrogels, these are shown to act as displays and agents for delivery of therapeutic payloads. Spatioselective control over surface chemistry is demonstrated via introduction of free acetylene groups in selected volumes, and their surface modification via “click chemistry”. We then utilize the surface anisotropy of these microstructures to self assemble them into larger architectures in case of particles, and to form unique cell-guiding scaffolds in case of fibers. Enabling the design of particles with multiple and distinct surface patterns or nano-compartments would help spur the development of the next generation of high throughput biomedical devices.