Cellular assays are the backbone of biological studies - be it for tissue modeling, drug discovery, therapeutics, or diagnostics. Two-dimensional (2D) cell culture has been deployed for several decades to garner physiologically relevant information and predict data before the cost-intensive animal testing. Although 2D techniques have been valuable for cellular assays, they have a colossal limitation - they do not adequately consider the natural three-dimensional (3D) microenvironment of the cells. As a result, they sometimes provide misleading statistics. Therefore, it is important to develop a 3D model that predicts cellular behaviors and their interaction with neighboring cells and extracellular matrix (ECM) in a more realistic manner. In recent biomedical research, various platforms have been modeled to generate 3D prototypes of tissues, spheroids, in vitro that could allow the study of cellular responses resembling in vivo environments, such as matrices, scaffolds, and devices. But most of these platforms have drawbacks such as lack of spheroid size control, low yield, or high cost associated with them. On the other hand, Amikagel is a low cost, high-fidelity platform that can facilitate the convenient generation of tumor and stem cell spheroids. Furthermore, Amikabeads are aminoglycoside-derived hydrogel microbeads derived from the same monomers as Amikagel. They are a versatile platform with several chemical groups that can be exploited for encapsulating the spheroids and investigating the delivery of bioactive compounds to the cells. This thesis is focused on engineering novel 3D tumor and stem cell models generated on Amikagel and encapsulated in Amikabeads for proximal delivery of bioactive compounds and applications in regenerative medicine.

Minimally invasive endovascular embolization procedures decrease surgery time, speed up recovery, and provide the possibility for more comprehensive treatment of aneurysms, arteriovenous malformations (AVMs), and hypervascular tumors. Liquid embolic agents (LEAs) are preferred over mechanical embolic agents, such as coils, because they achieve homogeneous filling of aneurysms and more complex angioarchitectures. The gold standard of commercially available LEAs is dissolved in dimethyl sulfoxide (DMSO), which has been associated with vasospasm and angiotoxicity. The aim of this study was to investigate amino acid substitution in an enzyme-degradable side group of an N-isopropylacrylamide (NIPAAm) copolymer for the development of a LEA that would be delivered in water and degrade at the rate that tissue is regenerated. NIPAAm copolymers have a lower critical solution temperature (LCST) due to their amphiphilic nature. This property enables them to be delivered as liquids through a microcatheter below their LCST and to solidify in situ above the LCST, which would result in the successful selective occlusion of blood vessels. Therefore, in this work, a series of poly(NIPAAm-co-peptide) copolymers with hydrophobic side groups containing the Ala-Pro-Gly-Leu collagenase substrate peptide sequence were synthesized as in situ forming, injectable copolymers.. The Gly-Leu peptide bond in these polypeptides is cleaved by collagenase, converting the side group into the more hydrophilic Gly-Ala-Pro-Gly-COOH (GAPG-COOH), thus increasing the LCST of the hydrogel after enzyme degradation. Enzyme degradation property and moderate mechanical stability convinces the use of these copolymers as liquid embolic agents.