UC San Diego

Polymers are a group of materials that consist of large molecules (macromolecules) arranged in a pattern of repeating small subunits. They can be classified into natural polymers and synthetic polymers, degradable and non-degradable polymers. A variety of processing techniques are available to process the polymers, including hot melt extrusion, additive manufacturing, and molding. The versatility of polymer science enables its broad applications to range from packaging, and automotive to biomedical concerns. Particularly, the application in biomedical fields has been of the utmost interest because of the hope of increased longevity and improved quality of life. We here investigated novel polymer engineering methods to improve the interface between materials science and biology and presented a couple of biomedical applications examples based on protein/ polymer composites and non-degradable conductive polymers. Virus nanoparticles (VNPs) (plant viruses in this thesis) are virus-based nanoparticles with highly symmetrical, polyvalent, and monodisperse structures. They can have icosahedral or rod-shaped geometry. Interestingly, the rod-shaped virus, tobacco mild green mosaic virus (TMGMV) presents as high as 1 GPa Young’s modulus and has been utilized as a hydrophilic nanofiller to strengthen the hydrogel networks in this thesis. Cowpea mosaic virus (CPMV) by itself is a potent cancer immunotherapy agent, however, multi-dosage injections are generally required for CPMV treatment. This brings challenges for patients’ compliance as well as difficulty in treating hard-to-inject tumors. Here, we introduced a hot melt extrusion (HME) fabrication method to manufacture a sustained CPMV delivery device. A lyophilization-based genomic material elimination method was accidentally discovered in the development of the CPMV implant. A small molecule STING agonist sustained delivery implant was further fabricated based on the reported HME method and the in vivo efficacy of the biomedical device was examined with murine models. Poly(3,4-ethylenedioxythiophene) (PEDOT) is so far the most conductive commercial conductive polymer, however, 3D printable PEDOT is still under development. We here developed a coagulation-bath-assisted method to pattern PEDOT hydrogel, which resulted in high conductivity and biological tissue-matched mechanical properties. A cortex-wide brain-machine interface was fabricated based on the developed technology, and its feasibility has been studied with an electrical stimulation experiment observed by a wide-field microscope. Polymer science is a highly multidisciplinary subject, we here separately presented the engineering methods of polymers to fabricate protein/polymer composites for drug delivery, and conductive polymers for bioelectronics. However, the idea of protein/polymer composites and bioelectronics can be combined and enabled a “living material” based on bioelectronics. The concept of wirelessly controllable contact lenses for immunotherapy has been proposed in the outlook of the thesis. With the hope of improved human health and increased living quality, the development from the perspective of polymer engineering was studied in this thesis and served for further research investigations.